git-hooks: show length of first line if it's too long

Change-Id: I164e4308c2a3e685bbc83cfde1cae5189839075e
Reviewed-on: https://gerrit.libreoffice.org/73556
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

.git-hooks/commit-msg

@@ -41,8 +41,9 @@ fi
 
 # ...and that it is not too long
 
-if [ "`head -n 1 $1 | wc -c`" -gt 79 ] ; then
-    abort "$1" "The first line is too long, please try to fit into 79 characters."
+len="`head -n 1 $1 | wc -c`"
+if [ "$len" -gt 79 ] ; then
+    abort "$1" "The first line is $len characters, please try to fit into 79 characters."
 fi
 
 fdo_regex='fdo#[0-9]+'