Regressions on releases/gcc-15 at commit r15-10807 vs commit r15-10796 on Linux/x86_64

[Haochen Jiang]

Regressions on releases/gcc-15 at commit r15-10807 vs commit r15-10796 on Linux/x86_64
New failures:
FAIL: gcc.dg/lto/save-temps c_lto_save-temps_0.o-c_lto_save-temps_0.o link,  -O -flto -save-temps

New passes:
FAIL: gcc.dg/lto/pr122515, ar returned 1: /export/home/haochenj/src/gcc-15-regression/bld/gcc/gcc-ar: Cannot find plugin 'liblto_plugin.so'
FAIL: gcc.dg/lto/pr122515, ar returned 1: /export/home/haochenj/src/gcc-15-regression/bld/gcc/gcc-ar: Cannot find plugin 'liblto_plugin.so'