perf_counter tools: add cpu_relax()/rmb() definitions for sh.

Simple cpu_relax()/rmb() stubs that perf needs, which were inadvertently
omitted from the sh HAVE_PERF_COUNTERS patch.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

tools/perf/perf.h

@@ -19,6 +19,16 @@
 #define cpu_relax()	asm volatile("" ::: "memory");
 #endif
 
+#ifdef __sh__
+#include "../../arch/sh/include/asm/unistd.h"
+#if defined(__SH4A__) || defined(__SH5__)
+# define rmb()		asm volatile("synco" ::: "memory")
+#else
+# define rmb()		asm volatile("" ::: "memory")
+#endif
+#define cpu_relax()	asm volatile("" ::: "memory")
+#endif
+
 #include <time.h>
 #include <unistd.h>
 #include <sys/types.h>