t/perf/fsmonitor: shorten DESC to basename

The full name is lengthy and makes it hard to read
Before:
7519.3: status (fsmonitor=/home/nipunn/src/server/.git/hooks/rs-git-fsmonitor) 0.02(0.01+0.00)

After
7519.3: status (fsmonitor=rs-git-fsmonitor) 0.03(0.02+0.00)

Signed-off-by: Nipunn Koorapati <nipunn@dropbox.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/perf/p7519-fsmonitor.sh

@@ -141,7 +141,11 @@ test_perf_w_drop_caches () {
 }
 
 test_fsmonitor_suite() {
-	DESC="fsmonitor=$INTEGRATION_SCRIPT"
+	if test -n "$INTEGRATION_SCRIPT"; then
+		DESC="fsmonitor=$(basename $INTEGRATION_SCRIPT)"
+	else
+		DESC="fsmonitor=disabled"
+	fi
 
 	test_perf_w_drop_caches "status ($DESC)" '
 		git status