In acline_init(), initialize ac_line to SRC_UNKNOWN. Previously

this could lead to the -n option effectively being ignored (in case
ac_line happened to be 0 aka SRC_AC), or other undefined behaviour.

PR:		169779
Submitted by:	Alex Gonzalez <loox at e-shell.net>
Reviewed by:	jhb
MFC after:	2 weeks

usr.sbin/powerd/powerd.c

@@ -279,6 +279,7 @@ static void
 acline_init(void)
 {
 	acline_mib_len = 4;
+	acline_status = SRC_UNKNOWN;
 
 	if (sysctlnametomib(ACPIAC, acline_mib, &acline_mib_len) == 0) {
 		acline_mode = ac_sysctl;