Very minor issues found with statical analysis.

The Clang Static Analyzer uncovered those issues:

- The variable "changed" in handlers.c is written to, but it's
  never read since that specific write, so the write is not
  necessary.

- In util.c, "tail" may be NULL. In that case, we shouldn't pass
  it to strlen because strlen's behavior is not defined when s is
  NULL.

- In util.c, "write_index" is incremented twice. It's never used
  anymore after being incremented once, so the second increment is
  not necessary.

src/handlers.c

@@ -751,7 +751,6 @@ int handle_normal_hints(void *data, xcb_connection_t *conn, uint8_t state, xcb_w
         con->base_height = base_height;
         DLOG("client's base_height changed to %d\n", base_height);
         DLOG("client's base_width changed to %d\n", base_width);
-        changed = true;
     }
 
     /* If no aspect ratio was set or if it was invalid, we ignore the hints */

src/util.c

@@ -199,7 +199,8 @@ char *resolve_tilde(const char *path) {
                 head = globbuf.gl_pathv[0];
                 result = scalloc(strlen(head) + (tail ? strlen(tail) : 0) + 1);
                 strncpy(result, head, strlen(head));
-                strncat(result, tail, strlen(tail));
+                if (tail)
+                    strncat(result, tail, strlen(tail));
         }
         globfree(&globbuf);
 
@@ -353,7 +354,7 @@ void i3_restart(bool forget_layout) {
 
         /* add the arguments we'll replace */
         new_argv[write_index++] = "--restart";
-        new_argv[write_index++] = restart_filename;
+        new_argv[write_index] = restart_filename;
 
         /* swap the argvs */
         start_argv = new_argv;