Change gw_gvFreeLayout return type to void

Author: IvanGoncharov

backend/src/layout_inline.h

@@ -5,7 +5,7 @@ typedef struct GVC_s GVC_t;
 typedef struct Agraph_s Agraph_t;
 
 int gw_gvLayoutDot(GVC_t *gvc, Agraph_t* graph);
-int gw_gvFreeLayout(Agraph_t* graph);
+void gw_gvFreeLayout(Agraph_t* graph);
 int gw_gvLayout(GVC_t *gvc, Agraph_t *g, const char *engine);
 
 #endif

backend/src/wasm_module.zig

@@ -333,7 +333,7 @@ pub export fn render(json_bytes: [*]u8, size: usize) WasmString {
             .output = null,
         });
     }
-    defer _ = graphviz.gw_gvFreeLayout(graphptr);
+    defer graphviz.gw_gvFreeLayout(graphptr);
 
     var responseDot: ?[:0]const u8 = null;
     defer freeCString(responseDot);