perf trace: Use $PERF_EXEC_PATH in canned report scripts

Set $PERF_EXEC_PATH before starting the record and report scripts, and
make them use it where necessary.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286723403.2955.205.camel@localhost>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/scripts/perl/bin/rwtop-report b/tools/perf/scripts/perl/bin/rwtop-report
index 93e698c..4918dba 100644
--- a/tools/perf/scripts/perl/bin/rwtop-report
+++ b/tools/perf/scripts/perl/bin/rwtop-report
@@ -17,7 +17,7 @@
     interval=$1
     shift
 fi
-perf trace $@ -s ~/libexec/perf-core/scripts/perl/rwtop.pl $interval
+perf trace $@ -s "$PERF_EXEC_PATH"/scripts/perl/rwtop.pl $interval