[clang] [clang] Implement -Wmissing-include-dirs (PR #94827)

[via cfe-commits]

================
@@ -1271,6 +1271,12 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
     if (VFS->setCurrentWorkingDirectory(WD->getValue()))
       Diag(diag::err_drv_unable_to_set_working_directory) << WD->getValue();
 
+  // Check for missing include directories
----------------
zmodem wrote:

nit: period at the end

https://github.com/llvm/llvm-project/pull/94827