Add -E cmake_llvm_rc to preprocess files for llvm-rc
llvm-rc requires preprocessed rc files. The CMake command line tool cmake_llvm_rc enables channing the preprocessor call and the resource compiler and make this appear as single compilation step.
When llvm-rc is detected as resource compiler, the RC compilation step is set to use this command.
Fixes: #20198 (closed)
Topic-rename: llvm-rc-preprocess
Edited by Brad King