Improve document for BUILD-WINDOWS.md

[honglei]

Just following the document BUILD-WINDOWS.md cannot build lsquic. So, I need to configure every header path and lib path manually as follows, I hope document can be improved or providing builded libs.

vcpkg install zlib:x64-windows-static
vcpkg install libevent:x64-windows-static
vcpkg install pcre:x64-windows-static

vcpkg integrate install

##BoringSSL Debug

cmake -DCMAKE_GENERATOR_PLATFORM=x64 --config Debug -DBUILD_SHARED_LIBS=OFF -DOPENSSL_NO_ASM=1 .
msbuild ALL_BUILD.vcxproj

##BoringSSL Release

cmake -DCMAKE_GENERATOR_PLATFORM=x64 --config Release -DBUILD_SHARED_LIBS=OFF -DOPENSSL_NO_ASM=1 .
msbuild ALL_BUILD.vcxproj

##Debug

set include=X:\QUIC\vcpkg\installed\x64-windows-static\include
set vclib=X:\QUIC\vcpkg\installed\x64-windows-static\debug\lib

cmake -DCMAKE_GENERATOR_PLATFORM=x64 -DBUILD_SHARED_LIBS=OFF   -DVCPKG_TARGET_TRIPLET=x64-windows-static -DCMAKE_BUILD_TYPE=Debug  -DPCRE_LIB=%vclib%\pcred.lib -DPCREPOSIX_LIB=%vclib%\pcreposixd.lib  -DZLIB_INCLUDE_DIR=%include%  -DZLIB_LIB=%vclib%\zlibd.lib -DEVENT_INCLUDE_DIR=%include% -DEVENT_LIB=%vclib%\event.lib -DCMAKE_TOOLCHAIN_FILE=X:/QUIC/vcpkg/scripts/buildsystems/vcpkg.cmake   -DBORINGSSL_LIB_decrepit=X:\QUIC\boringssl\decrepit\Debug\decrepit.lib -DBORINGSSL_LIB_ssl=X:\QUIC\boringssl\ssl\Debug\ssl.lib -DBORINGSSL_LIB_crypto=X:\QUIC\boringssl\crypto\Debug\crypto.lib .

msbuild ALL_BUILD.vcxproj 

##Release

set include=X:\QUIC\vcpkg\installed\x64-windows-static\include
set vclib=X:\QUIC\vcpkg\installed\x64-windows-static\lib

cmake -DCMAKE_GENERATOR_PLATFORM=x64 -DBUILD_SHARED_LIBS=OFF   -DVCPKG_TARGET_TRIPLET=x64-windows-static -DCMAKE_BUILD_TYPE=Release  -DPCRE_LIB=%vclib%\pcre.lib -DPCREPOSIX_LIB=%vclib%\pcreposix.lib  -DZLIB_INCLUDE_DIR=%include%  -DZLIB_LIB=%vclib%\zlib.lib -DEVENT_INCLUDE_DIR=%include% -DEVENT_LIB=%vclib%\event.lib -DCMAKE_TOOLCHAIN_FILE=X:/QUIC/vcpkg/scripts/buildsystems/vcpkg.cmake   -DBORINGSSL_LIB_decrepit=X:\QUIC\boringssl\decrepit\Release\decrepit.lib -DBORINGSSL_LIB_ssl=X:\QUIC\boringssl\ssl\Release\ssl.lib -DBORINGSSL_LIB_crypto=X:\QUIC\boringssl\crypto\Release\crypto.lib .

using lsquic.sln to do ALL_BUILD

[dtikhonov]

Thank you for the bug report and the suggested updates. You are right: these instructions are out of date. We will fix the document.

(To build on Windows, the authoritative steps are listed in appveyor.yml, which successfully builds on Windows.)

[TYoungSL]

appveyor-windows.yml has been updated per #350

There are additional steps needed to build a shared library (dll) but CMake flags -DBUILD_SHARED_LIBS=ON -DLSQUIC_SHARED_LIB=ON -DVCPKG_TARGET_TRIPLET=x64-windows -DCMAKE_WINDOWS_EXPORT_ALL_SYMBOLS=ON is a good starting point.

I'd like to contribute an appveyor-windows-shared.yml to build it if possible @litespeedtech @dtikhonov

I'm not overly familiar with appveyor, if I make a PR with that file does any wire-up in appveyor need to be done?

Can update BUILD-WINDOWS.md at the same time and cover static and shared build instructions. It'd be nice if a newer version of CMake could be required.