Test: gcc-15.1.1+20250524-0.1

[ASSI]

The native Gcc compilers have been updated to the latest upstream
snapshot version of the main development branch:

 gcc-15.1.1+20250524

This build incorporates the experimental v4 patch from T. Yano to use
the newlib locale function in libstdc++ so that other locales (aside
from "C") become usable.

Cygwin does not allow multiple versions of the compilers to be installed
concurrently.

For this build, the D compiler has been disabled since it does not
bootstrap due to the missing Phobos runtime on Cygwin.  No testing
beyond the compiler testsuite has been done.  Libgccjit is now building
and part of the release again.

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