cpp-id-data.h: Add extern "C".

* include/cpp-id-data.h: Add extern "C".
	* include/line-map.h: Likewise.
	* include/mkdeps.h: Likewise.
	* include/symtab.h: Likewise.
	* internal.h: Likewise.

From-SVN: r148051

libcpp/include/cpp-id-data.h

@@ -18,6 +18,10 @@ along with this program; see the file COPYING3.  If not see
 
 #include "cpplib.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #if !defined (HAVE_UCHAR) && !defined (IN_GCC)
 typedef unsigned char uchar;
 #endif
@@ -79,3 +83,7 @@ struct GTY(()) cpp_macro {
      tokens.  */
   unsigned int extra_tokens : 1;
 };
+
+#ifdef __cplusplus
+}
+#endif