Merge pull request #1181 from Exiv2/fix_gcc930_msys_cygwin

GCC 9.3.0 broken on MinGW/msys2 and CYGWIN (0.27->master)

cmake/compilerFlags.cmake

@@ -23,8 +23,8 @@ if ( MINGW OR UNIX OR MSYS ) # MINGW, Linux, APPLE, CYGWIN
 
     if (COMPILER_IS_GCC OR COMPILER_IS_CLANG)
 
-        # This fails under Fedora - MinGW - Gcc 8.3
+        # This fails under Fedora, MinGW GCC 8.3.0 and CYGWIN/MSYS 9.3.0
-        if (NOT MINGW AND NOT CMAKE_HOST_SOLARIS)
+        if (NOT (MINGW OR CMAKE_HOST_SOLARIS OR CYGWIN OR MSYS) )
             if (COMPILER_IS_GCC AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 8.0)
                 add_compile_options(-fstack-clash-protection -fcf-protection)
             endif()