Add -dwarf-debug-flags, which provides a way to embed the cc1 level options used
to compile a translation unit into the debug info for that file.
 - Used by parts of Darwin build process to check compiler flags, etc.
 - <rdar://problem/7256886> clang does not emit AT_APPLE_flags

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@91661 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Driver/ToolChains.cpp b/lib/Driver/ToolChains.cpp
index 420573d..0c2db8a 100644
--- a/lib/Driver/ToolChains.cpp
+++ b/lib/Driver/ToolChains.cpp
@@ -526,6 +526,12 @@
   return getArchName() == "x86_64";
 }
 
+bool Darwin::UseDwarfDebugFlags() const {
+  if (const char *S = ::getenv("RC_DEBUG_OPTIONS"))
+    return S[0] != '\0';
+  return false;
+}
+
 const char *Darwin::GetDefaultRelocationModel() const {
   return "pic";
 }