MSWin32: Support for bundled C++ source on Windows + Visual C++

[plicease]

this is the error from the appropriate tests. I've disabled C++ support for this combo until we can work this out.

# Subtest: build c++
    # corpus/ffi_build/project-cxx/foo1.cxx
    # corpus/ffi_build/project-cxx/foo2.cpp
    not ok 1 - no error

    #   Failed test 'no error'
    #   at t\ffi_build.t line 147.
    # +cl -nologo -GF -W3 -MD -DWIN32 -D_CONSOLE -DNO_STRICT -DWIN64 -D_CRT_SECURE_NO_DEPRECATE -D_CRT_NONSTDC_NO_DEPRECATE -D_WINSOCK_DEPRECATED_NO_WARNINGS -DPERL_TEXTMODE_SCRIPTS -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DWIN32_NO_REGISTRY -O1 -Zi -GL -fp:precise -IF:\dev\FFI-Platypus\blib\lib\auto\share\dist\FFI-Platypus\include -c corpus/ffi_build/project-cxx/foo1.cxx -Focorpus/ffi_build/project-cxx/tmpbuild.20372.1576119538/foo1.obj
    # foo1.cxx
    # +cl -nologo -GF -W3 -MD -DWIN32 -D_CONSOLE -DNO_STRICT -DWIN64 -D_CRT_SECURE_NO_DEPRECATE -D_CRT_NONSTDC_NO_DEPRECATE -D_WINSOCK_DEPRECATED_NO_WARNINGS -DPERL_TEXTMODE_SCRIPTS -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DWIN32_NO_REGISTRY -O1 -Zi -GL -fp:precise -IF:\dev\FFI-Platypus\blib\lib\auto\share\dist\FFI-Platypus\include -c corpus/ffi_build/project-cxx/foo2.cpp -Focorpus/ffi_build/project-cxx/tmpbuild.20372.1576119538/foo2.obj
    # foo2.cpp
    # D:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.24.28314\include\ostream(743): warning C4530: C++ exception handler used, but unwind semantics are not enabled. Specify /EHsc
    # corpus/ffi_build/project-cxx/foo2.cpp(20): note: see reference to function template instantiation 'std::basic_ostream<char,std::char_traits<char>> &std::operator <<<std::char_traits<char>>(std::basic_ostream<char,std::char_traits<char>> &,const char *)' being compiled
    # +cl -dll -nologo -debug -opt:ref,icf -ltcg -libpath:D:langperlvcx645.31.6libCORE -machine:AMD64 -subsystem:console,5.02 -dll corpus/ffi_build/project-cxx/tmpbuild.20372.1576119538/foo1.obj corpus/ffi_build/project-cxx/tmpbuild.20372.1576119538/foo2.obj -OUT:F:/dev/FFI-Platypus/.tmp/tmpbuild.Rti5w7/foo.dll
    # cl : Command line warning D9035 : option 'o' has been deprecated and will be removed in a future release
    # cl : Command line warning D9025 : overriding '/Ot' with '/Os'
    # cl : Command line warning D9025 : overriding '/Os' with '/Ot'
    # cl : Command line warning D9002 : ignoring unknown option '-dll'
    # cl : Command line warning D9002 : ignoring unknown option '-debug'
    # cl : Command line warning D9002 : ignoring unknown option '-ltcg'
    # cl : Command line warning D9002 : ignoring unknown option '-libpath:D:langperlvcx645.31.6libCORE'
    # cl : Command line warning D9002 : ignoring unknown option '-machine:AMD64'
    # cl : Command line warning D9002 : ignoring unknown option '-subsystem:console,5.02'
    # cl : Command line warning D9002 : ignoring unknown option '-dll'
    # cl : Command line warning D9002 : ignoring unknown option '-OU'
    # cl : Command line warning D9002 : ignoring unknown option '-OT'
    # cl : Command line warning D9002 : ignoring unknown option '-O:'
    # cl : Command line warning D9002 : ignoring unknown option '-OF'
    # cl : Command line warning D9002 : ignoring unknown option '-O:'
    # cl : Command line warning D9002 : ignoring unknown option '-O/'
    # cl : Command line warning D9002 : ignoring unknown option '-Oe'
    # cl : Command line warning D9002 : ignoring unknown option '-Ov'
    # cl : Command line warning D9002 : ignoring unknown option '-O/'
    # cl : Command line warning D9002 : ignoring unknown option '-OF'
    # cl : Command line warning D9002 : ignoring unknown option '-OF'
    # cl : Command line warning D9002 : ignoring unknown option '-OI'
    # cl : Command line warning D9002 : ignoring unknown option '-O-'
    # cl : Command line warning D9002 : ignoring unknown option '-OP'
    # cl : Command line warning D9002 : ignoring unknown option '-Ol'
    # cl : Command line warning D9002 : ignoring unknown option '-Oa'
    # cl : Command line warning D9002 : ignoring unknown option '-Op'
    # cl : Command line warning D9002 : ignoring unknown option '-Ou'
    # cl : Command line warning D9002 : ignoring unknown option '-O/'
    # cl : Command line warning D9002 : ignoring unknown option '-O.'
    # cl : Command line warning D9002 : ignoring unknown option '-Om'
    # cl : Command line warning D9002 : ignoring unknown option '-Op'
    # cl : Command line warning D9002 : ignoring unknown option '-O/'
    # cl : Command line warning D9002 : ignoring unknown option '-Om'
    # cl : Command line warning D9002 : ignoring unknown option '-Op'
    # cl : Command line warning D9002 : ignoring unknown option '-Ob'
    # cl : Command line warning D9002 : ignoring unknown option '-Ou'
    # cl : Command line warning D9002 : ignoring unknown option '-Ol'
    # cl : Command line warning D9002 : ignoring unknown option '-O.'
    # cl : Command line warning D9002 : ignoring unknown option '-OR'
    # cl : Command line warning D9002 : ignoring unknown option '-O5'
    # cl : Command line warning D9002 : ignoring unknown option '-Ow'
    # cl : Command line warning D9002 : ignoring unknown option '-O7'
    # cl : Command line warning D9002 : ignoring unknown option '-O/'
    # cl : Command line warning D9002 : ignoring unknown option '-Of'
    # cl : Command line warning D9002 : ignoring unknown option '-Oo'
    # cl : Command line warning D9002 : ignoring unknown option '-Oo'
    # cl : Command line warning D9002 : ignoring unknown option '-O.'
    # cl : Command line warning D9002 : ignoring unknown option '-Ol'
    # cl : Command line warning D9002 : ignoring unknown option '-Ol'
    # foo1.obj : MSIL .netmodule or module compiled with /GL found; restarting link with /LTCG; add /LTCG to the link command line to improve linker performance
    # LINK : fatal error LNK1561: entry point must be defined
    1..1
    # Looks like you failed 1 test of 1.
not ok 4 - build c++

#   Failed test 'build c++'
#   at t\ffi_build.t line 198.
# Subtest: alien
    1..0 # SKIP Test requires Acme::Alien::DontPanic 1.03
ok 5 # skip Test requires Acme::Alien::DontPanic 1.03
1..5
# Looks like you failed 1 test of 5.
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/5 subtests
        (less 1 skipped subtest: 3 okay)

Test Summary Report
-------------------
t\ffi_build.t (Wstat: 256 Tests: 5 Failed: 1)
  Failed test:  4
  Non-zero exit status: 1
Files=1, Tests=5,  1 wallclock secs ( 0.02 usr +  0.01 sys =  0.03 CPU)
Result: FAIL