lib/common.sh: add 'lock_close'; use it as appropriate.

`lock_close FD` is easier to remember than 'exec FD>&-`; and is especially
easier if FD is a variable (though that isn't actually taken advantage of
here).

This uses Bash 4.1+ `exec {var}>&-`, rather than the clunkier
`eval exec "$var>&-"` that was necessary in older versions of Bash.
Thanks to Dave Reisner for pointing this new bit of syntax out to me
the last time I submitted this (back in 2014, 4.1 had just come out).

1 files changed, 1 insertions, 1 deletions

diff --git a/archbuild.in b/archbuild.in
index 9c5d706..c1917c3 100644
--- a/archbuild.in
+++ b/archbuild.in
@@ -58,7 +58,7 @@ if ${clean_first} || [[ ! -d "${chroots}/${repo}-${arch}" ]]; then
 		fi
 		rm -rf --one-file-system "${copy}"
 	done
-	exec 9>&-
+	lock_close 9
 
 	rm -rf --one-file-system "${chroots}/${repo}-${arch}"
 	mkdir -p "${chroots}/${repo}-${arch}"