Fixed issue with empty command delimiter

This meant that the delimiters were added when when both the icon and
output where empty.

dwmblocks.c

@@ -56,6 +56,8 @@ void getcmd(const Block *block, char *output)
 	int i = strlen(block->icon);
 	fgets(output+i, CMDLENGTH-i-delimLen, cmdf);
 	i = strlen(output);
+	if (i == 0)//return if block and command output are both empty
+		return;
 	if (delim[0] != '\0') {
 		//only chop off newline if one is present at the end
 		i = output[i-1] == '\n' ? i-1 : i;