[patch resend] compiler, clang: suppress warning for unused static inline functions

[David Rientjes]

GCC explicitly does not warn for unused static inline functions for
-Wunused-function.  The manual states:

	Warn whenever a static function is declared but not defined or
	a non-inline static function is unused.

Clang does warn for static inline functions that are unused.

It turns out that suppressing the warnings avoids potentially complex
#ifdef directives, which also reduces LOC.

Suppress the warning for clang.

Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
 This is a resend of my patch from http://marc.info/?t=149565969200006 
 that did not seem to end very productively, but I'm not in a position to
 insist.

 include/linux/compiler-clang.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -15,3 +15,10 @@
  * with any version that can compile the kernel
  */
 #define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
+
+/*
+ * GCC does not warn about unused static inline functions for
+ * -Wunused-function.  This turns out to avoid the need for complex #ifdef
+ * directives.  Suppress the warning in clang as well.
+ */
+#define inline inline __attribute__((unused))