Tobias Kühne

**Describe the bug** `make check` fails with the following console output (shortened): ``` PASS: testc.exe PASS: testp.exe PASS: testcu.exe ============================================================================ Testsuite summary for onig 6.1.3 ============================================================================ # TOTAL: 3 #...

Use separate flags for MinGW and Cygwin, as `-avoid-version` not not …

1

…desired for Cygwin and `-Wl,--nxcompat -Wl,--dynamicbase` may cause trouble in conjuction with other DLLs as discussed in PR #175.

[C_STANDARD](https://cmake.org/cmake/help/v3.17/prop_tgt/C_STANDARD.html#prop_tgt:C_STANDARD) is `99` instead of `C99`.