lib: Move compiler.h to <openvswitch/compiler.h>

The following macros are renamed to avoid conflicts with other headers:
 * WARN_UNUSED_RESULT to OVS_WARN_UNUSED_RESULT
 * PRINTF_FORMAT to OVS_PRINTF_FORMAT
 * NO_RETURN to OVS_NO_RETURN

Signed-off-by: Thomas Graf <tgraf@noironetworks.com>
Acked-by: Ben Pfaff <blp@nicira.com>

lib/command-line.h

@@ -41,7 +41,7 @@ void proctitle_init(int argc, char **argv);
 #define proctitle_set setproctitle
 #else
 void proctitle_set(const char *, ...)
-    PRINTF_FORMAT(1, 2);
+    OVS_PRINTF_FORMAT(1, 2);
 #endif
 void proctitle_restore(void);