Makefiles: Set Clang CPP compiler flags in a single location, instead of scattered throughout the project Makefiles.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@105638 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/Makefile b/Makefile
index 7b2a365..acb620d 100644
--- a/Makefile
+++ b/Makefile
@@ -32,6 +32,12 @@
 # Include LLVM common makefile.
 include $(LEVEL)/Makefile.common
 
+# Set common Clang build flags.
+CPP.Flags += -I$(PROJ_SRC_DIR)/$(CLANG_LEVEL)/include -I$(PROJ_OBJ_DIR)/$(CLANG_LEVEL)/include
+ifdef CLANG_VENDOR
+CPP.Flags += -DCLANG_VENDOR='"$(CLANG_VENDOR) "'
+endif
+
 ###
 # Clang Top Level specific stuff.