Allow building on machines without apm(4) support.

Index: clients/lcdproc/machine_OpenBSD.c
--- clients/lcdproc/machine_OpenBSD.c.orig
+++ clients/lcdproc/machine_OpenBSD.c
@@ -50,7 +50,9 @@
 #include <sys/mount.h>
 #include <sys/time.h>
 #include <sys/user.h>
+#ifdef WITH_APM
 #include <machine/apmvar.h>
+#endif
 #include <kvm.h>
 #include <errno.h>
 
@@ -97,13 +99,16 @@ machine_close(void)
 int
 machine_get_battstat(int *acstat, int *battflag, int *percent)
 {
+#ifdef WITH_APM
 	int apmd;
 	struct apm_power_info api;
+#endif
 
 	*acstat = LCDP_AC_ON;
 	*battflag = LCDP_BATT_ABSENT;
 	*percent = 100;
 
+#ifdef WITH_APM
 	if ((apmd = open("/dev/apm", O_RDONLY)) == -1) {
 		perror("get_battstat_open");
 		return (TRUE);
@@ -150,6 +155,7 @@ machine_get_battstat(int *acstat, int *battflag, int *
 	*percent = api.battery_life;
 
 	close(apmd);
+#endif
 
 	return (TRUE);
 }