Introduce the abseil-redundant-strcat-calls check.

This flags redundant calls to absl::StrCat where the result is being passed to another call to absl::StrCat or absl::StrAppend. Patch by Hugo Gonzalez and Samuel Benzaquen.

llvm-svn: 340918
GitOrigin-RevId: ca5f775dbef8fa07d0fd4935e247e8865e324a6e
8 files changed