configure: Use default systemd path with prefix

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Fabio M. Di Nitto <fdinitto@redhat.com>

configure.ac

@@ -26,6 +26,8 @@ AC_CANONICAL_HOST
 AC_LANG([C])
 
 dnl Fix default variables - "prefix" variable if not specified
+systemddir=${prefix}/lib/systemd/system
+
 if test "$prefix" = "NONE"; then
 	prefix="/usr"
 
@@ -37,6 +39,9 @@ if test "$prefix" = "NONE"; then
 	if test "$sysconfdir" = "\${prefix}/etc"; then
 		sysconfdir="/etc"
 	fi
+	if test "$systemddir" = "NONE/lib/systemd/system"; then
+		systemddir=/lib/systemd/system
+	fi
 	dnl Fix "libdir" variable if not specified
 	if test "$libdir" = "\${exec_prefix}/lib"; then
 		if test -e /usr/lib64; then
@@ -160,7 +165,7 @@ AC_ARG_WITH([initddir],
 AC_ARG_WITH([systemddir],
 	[  --with-systemddir=DIR   : path to systemd unit files directory. ],
 	[ SYSTEMDDIR="$withval" ],
-	[ SYSTEMDDIR="/lib/systemd/system" ])
+	[ SYSTEMDDIR="$systemddir" ])
 
 AC_ARG_ENABLE([qdevices],
 	[  --disable-qdevices              : Quorum devices support ],,