avoid using config.h in public headers

This is the only usage in clang's headers, and it's for a define
that only exists on CMake builds for the sake of the MSVC compiler,
so just use an ifdef instead.

Also add an include for config.h in a file that actually needs it,
and was picking it up by accident indirectly.

llvm-svn: 133710

clang/include/clang/Basic/FileManager.h

@@ -21,10 +21,13 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/Support/Allocator.h"
-#include "llvm/Config/config.h" // for mode_t
 // FIXME: Enhance libsystem to support inode and other fields in stat.
 #include <sys/types.h>
 
+#ifdef _MSC_VER
+typedef unsigned short mode_t;
+#endif
+
 struct stat;
 
 namespace llvm {

clang/lib/Frontend/CompilerInstance.cpp

@@ -38,6 +38,7 @@
 #include "llvm/Support/Program.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/system_error.h"
+#include "llvm/Config/config.h"
 using namespace clang;
 
 CompilerInstance::CompilerInstance()