i3lock: fix pam configuration file

pam_tally(i3lock:auth): Error opening /var/log/faillog for update

pam_tally doesn't have the necessary privileges to write to
/var/log/faillog.
Replace 'login' with 'system-auth' fix the issue.

Fix taken from Gentoo.

srcpkgs/i3lock/template

@@ -1,7 +1,7 @@
 # Template file for 'i3lock'
 pkgname=i3lock
 version=2.7
-revision=1
+revision=2
 hostmakedepends="pkg-config"
 makedepends="libev-devel cairo-devel pam-devel libxkbcommon-devel
  xcb-util-devel xcb-util-image-devel"
@@ -14,6 +14,7 @@ distfiles="http://i3wm.org/i3lock/i3lock-${version}.tar.bz2"
 checksum=6882183ed0eca439e3ad1ae3e9d48b4d0a0b6f075e3850b46bf84aec97538fe2
 
 do_build() {
+	sed -i 's:login:system-auth:' i3lock.pam
 	make CC=$CC ${makejobs}
 }
 do_install() {