[PATCH] deprecated function attribute

This patch adds support for usage of the attribute as "deprecated" and
is backward-compatible.  Usage is:

	int deprecated foo(void)

etc..

If we mark a function as deprecated, then each use of the function emits
a warning like:

	foo.c:12: warning: `baz' is deprecated (declared at bar.c:60)

Which is very informative, giving both the location of each usage and
where the little bastard is declared.

include/linux/compiler.h

@@ -13,6 +13,19 @@
 #define likely(x)	__builtin_expect((x),1)
 #define unlikely(x)	__builtin_expect((x),0)
 
+/*
+ * Allow us to mark functions as 'deprecated' and have gcc emit a nice
+ * warning for each use, in hopes of speeding the functions removal.
+ * Usage is:
+ * 		int deprecated foo(void)
+ * and then gcc will emit a warning for each usage of the function.
+ */
+#if __GNUC__ >= 3
+#define deprecated	__attribute__((deprecated))
+#else
+#define deprecated
+#endif
+
 /* This macro obfuscates arithmetic on a variable address so that gcc
    shouldn't recognize the original var, and make assumptions about it */
 #define RELOC_HIDE(ptr, off)					\