[cmake] Fix path to LLVMConfig.cmake for multi-config builds

D139623 replaces CMAKE_CFG_INTDIR
with '.' for multi-config builds. However, this change has
not been reflected in mlir, flang, polly, lld, and clang.
The patch updates the path to LLVMConfig.cmake for those
projects.

Reviewed By: sebastian-ne

Differential Revision: https://reviews.llvm.org/D141538

GitOrigin-RevId: eb4aa6c7a5f22583e319aaaae3f6ee73cbc5464a
1 file changed