Commit #167996 moved VecLib into TargetOptions and ensured clang
properly sets it. However, some LTO backend code paths were still
creating _TargetLibraryInfoImpl_ without passing the VecLib parameter
from `TargetMachine::Options`.
This PR completes the fix by ensuring that:
_LTOBackend.cpp, ThinLTOCodeGenerator.cpp, UpdateCompilerUsed.cpp_ all
pass `TM->Options.VecLib` when constructing _TargetLibraryInfoImpl_.
Without this fix, vector library information (e.g., -fveclib=ArmPL)
would not be properly recognized during LTO optimization and code
generation, potentially causing incorrect optimizations or linker errors
when vector library functions are referenced.
edf80dce39