perf_counter tools: Cleanup Makefile

We currently build perf-stat/record etc, only to do nothing
with them.  We also install the perf binary in two places,
$prefix/bin and $perfexec_instdir, which appears to be for
binaries which perf would exec were a command not linked in.
Correct this, and comment out broken/incomplete targets dist
and coverage.

Signed-off-by: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: John Kacur <jkacur@redhat.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>