Without the change mingw32-gcc fails to build as:
In file included from /build/gcc-11.2.0/libstdc++-v3/libsupc++/cxxabi.h:49,
from ../../../../gcc-11.2.0/libstdc++-v3/libsupc++/atexit_thread.cc:24:
../../../../gcc-11.2.0/libstdc++-v3/libsupc++/atexit_thread.cc:36:3: error: 'int __cxxabiv1::__cxa_thread_atexit(void (*)(void*), void*, void*)' should have been declared inside '__cxxabiv1'
36 | _GLIBCXX_NOTHROW
| ^~~~~~~~~~~~~~~~
../../../../gcc-11.2.0/libstdc++-v3/libsupc++/atexit_thread.cc:34:1: error: conflicting declaration of C function 'int __cxxabiv1::__cxa_thread_atexit(void (*)(void*), void*, void*)'
34 | __cxxabiv1::__cxa_thread_atexit (void (*dtor)(void *),
| ^~~~~~~~~~
The change follows upstream change introduced in
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=7fc0f78c3f43af1967cb7b1ee8f4947f3b890aa2
Sergei Trofimovich