merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/t/perf/p4001-diff-no-index.sh

@@ -0,0 +1,22 @@
+#!/bin/sh
+
+test_description="Test diff --no-index performance"
+
+. ./perf-lib.sh
+
+test_perf_large_repo
+test_checkout_worktree
+
+file1=$(git ls-files | tail -n 2 | head -1)
+file2=$(git ls-files | tail -n 1 | head -1)
+
+test_expect_success "empty files, so they take no time to diff" "
+	echo >$file1 &&
+	echo >$file2
+"
+
+test_perf "diff --no-index" "
+	git diff --no-index $file1 $file2 >/dev/null
+"
+
+test_done