Test: gcc-13.4.1+20260610-0.1

[ASSI]

The native Gcc compilers have been updated to the latest upstream
snapshot version of the gcc-13 branch:

 gcc-13.4.1+20260610

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.  It also adds a patch to fix a Windows handle
leak when using std::mutex from libstdc++.

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