[Mod] mpt/check/libcxx.hpp: GCC 13 added the mcfgthread backend for W…

…indows which the Debian MinGW-w64 GCC packages now use in place of the old Win32 backend. Clarify error message. We cannot detect mcfgthread vs. pthread, thus we cannot warn if mcfgthread is selected and an unsupported (<Win7) Windows version is targeted.

git-svn-id: https://source.openmpt.org/svn/openmpt/trunk/OpenMPT@20656 56274372-70c3-4bfc-bfc3-4c3a0b034d27

src/mpt/check/libcxx.hpp

@@ -8,8 +8,8 @@
 #include "mpt/base/detect_quirks.hpp"
 
 #ifndef MPT_CHECK_LIBCXX_IGNORE_WARNING_NO_THREADS
-#if MPT_OS_WINDOWS && MPT_WIN_BEFORE(MPT_WIN_VISTA) && MPT_LIBCXX_GNU_AT_LEAST(13) && !defined(_GLIBCXX_HAS_GTHREADS)
-#error "GNU libstdc++ is compiled without gthreads support (likely due to using Win32 threading model as opposed to POSIX threading model. This a severely crippled C++11 implementation and no is no longer supported for targetting Windows before Vista as of release 13 because non-threading standard library headers fail to compile."
+#if MPT_OS_WINDOWS && MPT_WIN_BEFORE(MPT_WIN_7) && MPT_LIBCXX_GNU_AT_LEAST(13) && !defined(_GLIBCXX_HAS_GTHREADS)
+#error "GNU libstdc++ is compiled without gthreads support (likely due to using Win32 threading model as opposed to POSIX or mcfgthread threading model. This a severely crippled C++11 implementation and no is no longer supported ofr libstdc++ version 13 or later."
 #endif
 #endif