perf_counter tools: when no command is feed to perfstat, display help and exit
perf_counter tools: when no command is feed to perfstat, display help and exit

Signed-off-by: Wu Fengguang <24f7fe9d205c8a9f6ade0c2894e14303ca16087f@intel.com>
Acked-by: Peter Zijlstra <645ca7d3a8d3d4f60557176cd361ea8351edc32b@chello.nl>
Cc: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org>
Signed-off-by: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@elte.hu>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas