perf tools: Notify user when unrecognized event is specified
perf tools: Notify user when unrecognized event is specified

Previously no indication was given about what went wrong.

Signed-off-by: Marti Raudsepp <fd5da480b758a78208111e6ae5c6806e1f887137@juffo.org>
Cc: Peter Zijlstra <645ca7d3a8d3d4f60557176cd361ea8351edc32b@chello.nl>
Cc: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org>
LKML-Reference: <3cb7dd4c8197d79cd7c1a5ef2fc348fde6b252e2@localhost>
Signed-off-by: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@elte.hu>

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