ipc: return signed int for container positions

If we use json as a language-agnostic representation, it makes sense to
use proper signed integers here.

RELEASE-NOTES-next

@@ -34,3 +34,5 @@ strongly encouraged to upgrade.
   • i3bar: exit with 1 when a wrong command line argument is used
   • fix commented-out rofi call in default i3 config
   • clear pixmap before drawing to prevent visual garbage
+  • ipc: return proper signed int for container positions: negative values were
+    returned as large 32 bits integers

src/ipc.c

@@ -235,9 +235,9 @@ static void dump_rect(yajl_gen gen, const char *name, Rect r) {
     ystr(name);
     y(map_open);
     ystr("x");
-    y(integer, r.x);
+    y(integer, (int32_t)r.x);
     ystr("y");
-    y(integer, r.y);
+    y(integer, (int32_t)r.y);
     ystr("width");
     y(integer, r.width);
     ystr("height");