radical re-formatting 1/3: Fix spacing

Fixes coding style. Formatting commits suck, incoherent coding style
sucks more.
https://suckless.org/coding_style/

components/battery.c

@@ -227,7 +227,7 @@
 			return NULL;
 
 		switch (state) {
-			case 0:
+		case 0: /* FALLTHROUGH */
 		case 2:
 			return "+";
 		case 1:

slstatus.c

@@ -58,7 +58,7 @@ main(int argc, char *argv[])
 	ARGBEGIN {
 	case '1':
 		done = 1;
-			/* fallthrough */
+		/* FALLTHROUGH */
 	case 's':
 		sflag = 1;
 		break;