fix some memory leaks when user passes command line arguments twice (Thanks Tiago)

i3-input/i3-input.h

@@ -4,6 +4,13 @@
 #include <err.h>
 
 #define die(...) errx(EXIT_FAILURE, __VA_ARGS__);
+#define FREE(pointer) do { \
+        if (pointer != NULL) { \
+                free(pointer); \
+                pointer = NULL; \
+        } \
+} \
+while (0)
 
 char *convert_ucs_to_utf8(char *input);
 char *convert_utf8_to_ucs2(char *input, int *real_strlen);