t/perf/p7519: speed up test on Windows

Change p7519 to use `test_seq` and `xargs` rather than a `for` loop
to touch thousands of files.  This takes minutes off of test runs
on Windows because of process creation overhead.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/perf/p7519-fsmonitor.sh

@@ -98,6 +98,13 @@ trace_stop () {
 	fi
 }
 
+touch_files () {
+	n=$1 &&
+	d="$n"_files &&
+
+	(cd $d && test_seq 1 $n | xargs touch )
+}
+
 test_expect_success "one time repo setup" '
 	# set untrackedCache depending on the environment
 	if test -n "$GIT_PERF_7519_UNTRACKED_CACHE"
@@ -119,10 +126,11 @@ test_expect_success "one time repo setup" '
 	fi &&
 
 	mkdir 1_file 10_files 100_files 1000_files 10000_files &&
-	for i in $(test_seq 1 10); do touch 10_files/$i || return 1; done &&
+	: 1_file directory should be left empty &&
-	for i in $(test_seq 1 100); do touch 100_files/$i || return 1; done &&
+	touch_files 10 &&
-	for i in $(test_seq 1 1000); do touch 1000_files/$i || return 1; done &&
+	touch_files 100 &&
-	for i in $(test_seq 1 10000); do touch 10000_files/$i || return 1; done &&
+	touch_files 1000 &&
+	touch_files 10000 &&
 	git add 1_file 10_files 100_files 1000_files 10000_files &&
 	git commit -qm "Add files" &&
 
@@ -199,15 +207,15 @@ test_fsmonitor_suite () {
 
 	# Update the mtimes on upto 100k files to make status think
 	# that they are dirty.  For simplicity, omit any files with
-	# LFs (i.e. anything that ls-files thinks it needs to dquote).
+	# LFs (i.e. anything that ls-files thinks it needs to dquote)
-	# Then fully backslash-quote the paths to capture any
+	# and any files with whitespace so that they pass thru xargs
-	# whitespace so that they pass thru xargs properly.
+	# properly.
 	#
 	test_perf_w_drop_caches "status (dirty) ($DESC)" '
 		git ls-files | \
 			head -100000 | \
 			grep -v \" | \
-			sed '\''s/\(.\)/\\\1/g'\'' | \
+			grep -v " ." | \
 			xargs test-tool chmtime -300 &&
 		git status
 	'