Mark unused parameters, fix compiler warnings

components/battery.c

@@ -52,11 +52,13 @@
 	#include <unistd.h>
 
 	const char *
-	battery_perc(const char *null)
+	battery_perc(const char *bat)
 	{
 		struct apm_power_info apm_info;
 		int fd;
 
+		UNUSED(bat); /* no way to specify battery on OpenBSD */
+
 		fd = open("/dev/apm", O_RDONLY);
 		if (fd < 0) {
 			fprintf(stderr, "open '/dev/apm': %s\n", strerror(errno));
@@ -88,6 +90,8 @@
 			{ APM_AC_OFF,     "-" },
 		};
 
+		UNUSED(bat); /* no way to specify battery on OpenBSD */
+
 		fd = open("/dev/apm", O_RDONLY);
 		if (fd < 0) {
 			fprintf(stderr, "open '/dev/apm': %s\n", strerror(errno));