[PGO] Cherry-pick CSPGO LTO linker argument fix#12893

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mustartt wants to merge 2 commits intostable/21.xfrom

hjiang/cherry-pick-driver-cspgo-lto-args

Commits on May 4, 2026

[Darwin][Clang][PGO] Pass CSPGO related flags to ld when using libLTO.dylib (#195020)
mustartt
committed
[NFC][Darwin] Use add -fuse-ld=ld for Darwin CSPGO use test (#195721)
mustartt
committed