fix: restore systemd unit install path

Signed-off-by: Peter Jung <admin@ptr1337.dev>

Author: ptr1337

configure.ac

@@ -34,7 +34,7 @@ PKG_PROG_PKG_CONFIG
 AC_ARG_WITH([systemdsystemunitdir],
 	[AS_HELP_STRING([--with-systemdsystemunitdir=DIR], [Directory for systemd service files])],
 	[], [with_systemdsystemunitdir=$($PKG_CONFIG --variable=systemdsystemunitdir systemd)])
-AS_IF(["x$with_systemdsystemunitdir" != xno], [
+AS_IF([test "x$with_systemdsystemunitdir" != xno], [
         AC_SUBST([systemdsystemunitdir], [$with_systemdsystemunitdir])
 ])