perf tools: Remove unused cpu_relax() macros

Since 195564390210 ("perf_counter: kerneltop: simplify data_head read")
we do not use it, and this was way back in 2009, remove it before some
other arch maintainer adds its implementation, like so many did,
needlessly :-)

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-3l2su9c58eaq4twjzrf9uu08@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/perf-sys.h

@@ -10,12 +10,10 @@
 #include <asm/barrier.h>
 
 #if defined(__i386__)
-#define cpu_relax()	asm volatile("rep; nop" ::: "memory");
 #define CPUINFO_PROC	{"model name"}
 #endif
 
 #if defined(__x86_64__)
-#define cpu_relax()	asm volatile("rep; nop" ::: "memory");
 #define CPUINFO_PROC	{"model name"}
 #endif
 
@@ -44,7 +42,6 @@
 #endif
 
 #ifdef __ia64__
-#define cpu_relax()	asm volatile ("hint @pause" ::: "memory")
 #define CPUINFO_PROC	{"model name"}
 #endif
 
@@ -53,7 +50,6 @@
 #endif
 
 #ifdef __aarch64__
-#define cpu_relax()	asm volatile("yield" ::: "memory")
 #endif
 
 #ifdef __mips__
@@ -73,14 +69,9 @@
 #endif
 
 #ifdef __tile__
-#define cpu_relax()	asm volatile ("mfspr zero, PASS" ::: "memory")
 #define CPUINFO_PROC    {"model name"}
 #endif
 
-#ifndef cpu_relax
-#define cpu_relax() barrier()
-#endif
-
 static inline int
 sys_perf_event_open(struct perf_event_attr *attr,
 		      pid_t pid, int cpu, int group_fd,