Bug#1092866: gnat-15 20250112 ftbfs on armel/armhf

[Nicolas Boulenguez]

Source: gcc-15
Followup-For: Bug #1092866

Hello.
Thank you for adapting the time64 patches in 15-2025014-1.
I have updated the gcc-15 branch with v15 from PR Ada/114065, and
removed large parts that Debian does not need in the hope to reduce
the rebasing burden.