Revert "fix: unset LLVM CPPFLAGS when llvm is not used as the compiler" This reverts commit a8d76c6b538f9bc09243b13387cc83478537cde1.
Revert "fix: unset LLVM CPPFLAGS when llvm is not used as the compiler" This reverts commit a8d76c6b538f9bc09243b13387cc83478537cde1.