git: c6bcacc7c9d8..4b5393dfb492 - vendor/llvm-project/release-18.x - vendor branch updated

[Dimitry Andric]

The branch vendor/llvm-project/release-18.x has been updated by dim:

URL: https://cgit.FreeBSD.org/src/log/?id=c6bcacc7c9d8..4b5393dfb492

4b5393dfb492 Vendor import of llvm-project branch release/18.x 
llvmorg-18.1.7-0-g768118d1ad38.