"make check" times

[DJ Delorie]

Andreas Schwab <schwab@linux-m68k.org> writes:
> Never expand a variable unquoted.

How's this?  Also, comment updated to note we assume "echo" is a
builtin.

>From 98e461fd50f1617acc78caeaa70547b92a54cf5c Mon Sep 17 00:00:00 2001
From: DJ Delorie <dj@redhat.com>
Date: Wed, 1 Apr 2020 15:33:00 -0400
Subject: Optimize scripts/merge-test-results.sh

The inner loop is called thousands of times per "make check" even
if there's otherwise nothing to do.  Avoid calling /bin/head all
those times when a builtin will do.

diff --git a/scripts/merge-test-results.sh b/scripts/merge-test-results.sh
index 573a44d8cf..e75123a730 100755
--- a/scripts/merge-test-results.sh
+++ b/scripts/merge-test-results.sh
@@ -35,7 +35,12 @@ case $type in
     subdir=${subdir:+$subdir/}
     for t in "$@"; do
       if [ -s "$objpfx$t.test-result" ]; then
-	head -n1 "$objpfx$t.test-result"
+	# This loop is called thousands of times even when there's
+	# nothing to do.  Avoid using non-built-in commands (like
+	# /bin/head) where possible.  We assume "echo" is typically a
+	# built-in.
+	read line < "$objpfx$t.test-result"
+	echo "$line"
       else
 	echo "UNRESOLVED: $subdir$t"
       fi