In code we use #include "llvm/Lib/Header.h" which is located in
"llvm/include/llvm/Lib/Header.h", so we use "llvm/include/" as a header
search path. We should put modulemaps in the same directory and
shouldn't rely on clang to search in immediate subdirectories.
rdar://106677321
Disabling the code with the macro is not intended. Want to show which code is responsible for module map search in subdirectories and which code to disable in case you want to test locally.