perf/run: add GIT_PERF_DIRS_OR_REVS

This environment variable can be set to some revisions or
directories whose Git versions should be tested, in addition
to the revisions or directories passed as arguments to the
'run' script.

This enables a "perf.dirsOrRevs" configuration variable to
be used to set revisions or directories whose Git versions
should be tested.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/perf/run

@@ -113,6 +113,9 @@ get_var_from_env_or_config () {
 get_var_from_env_or_config "GIT_PERF_REPEAT_COUNT" "perf.repeatCount" 3
 export GIT_PERF_REPEAT_COUNT
 
+get_var_from_env_or_config "GIT_PERF_DIRS_OR_REVS" "perf.dirsOrRevs"
+set -- $GIT_PERF_DIRS_OR_REVS "$@"
+
 GIT_PERF_AGGREGATING_LATER=t
 export GIT_PERF_AGGREGATING_LATER