lang/gcc1?: further improvements for powerpc64*

1. Backport of e8385ea3b57862ce6c6ace5e6973b96cf238f4b6. Fixes libgcc

on powerpc64*, found with octave crashing.

2. Merge https://gcc.gnu.org/pipermail/gcc-patches/2026-July/723975.html,

not yet upstreamed, but allows to build all the remaining failing ports
due to ld128 switch for powerpc64le.

Differential Revision: https://reviews.freebsd.org/D58116