Build: find c-pragma.h,c-common.h regardless of gcc version

Add an extra -I line for the non-flattened location, then change all
inclusions to rely on the preprocessor search path to find the file.  It
is legal to specify a non-existent directory in the search path, so this
will work with both old and new layouts.

Author: Kevin Pyle

Makefile

@@ -97,7 +97,7 @@ PYTHON_CONFIG=python-config
 PYTHON_INCLUDES=$(shell $(PYTHON_CONFIG) --includes)
 PYTHON_LIBS=$(shell $(PYTHON_CONFIG) --libs)
 
-CPPFLAGS+= -I$(GCCPLUGINS_DIR)/include -I. $(PYTHON_INCLUDES)
+CPPFLAGS+= -I$(GCCPLUGINS_DIR)/include -I$(GCCPLUGINS_DIR)/include/c-family -I. $(PYTHON_INCLUDES)
 # Allow user to pick optimization, choose whether warnings are fatal,
 # and choose debugging information level.
 CFLAGS?=-O2 -Werror -g

gcc-python-option.c

@@ -20,7 +20,7 @@
 #include <Python.h>
 #include "gcc-python.h"
 #include "gcc-python-wrappers.h"
-#include "c-family/c-common.h" /* for warn_format */
+#include "c-common.h" /* for warn_format */
 #include "diagnostic.h"
 
 

gcc-python.c

@@ -34,7 +34,12 @@ int plugin_is_GPL_compatible;
 #include "cgraph.h"
 #include "opts.h"
 
-#include "c-family/c-pragma.h" /* for parse_in */
+/*
+ * Use an unqualified name here and rely on dual search paths to let the
+ * compiler find it.  This deals with c-pragma.h moving to a
+ * subdirectory in newer versions of gcc.
+ */
+#include "c-pragma.h" /* for parse_in */
 
 #if 0
 #define LOG(msg) \