[lit] Prevent "lld" from being substituted by LIT in llvm-driver tests (#191893)
We are seeing test failures in "passthrough-lld.test" as LIT
substitutes the "ld.lld" string in the test file to the full
path to the lld. However, the "-flavor" flag does not expect
a full path. It just need a name of the linker so it fails.
This patch modifies the lld matching regex in the use_lld
function in llvm/utils/lit/lit/llvm/config.py. It prevents
LIT from substitute any lld tool strings that are not
standalone.