perf time-utils: Adopt rdclock() from perf.h

Seems to be a better place for this function to live, further shrinking
the hodge-podge that perf.h was.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-0zzt1u9rpyjukdy1ccr2u5r9@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/perf.h

@@ -2,17 +2,8 @@
 #ifndef _PERF_PERF_H
 #define _PERF_PERF_H
 
-#include <time.h>
 #include <stdbool.h>
 
-static inline unsigned long long rdclock(void)
-{
-	struct timespec ts;
-
-	clock_gettime(CLOCK_MONOTONIC, &ts);
-	return ts.tv_sec * 1000000000ULL + ts.tv_nsec;
-}
-
 #ifndef MAX_NR_CPUS
 #define MAX_NR_CPUS			2048
 #endif