Expose gc_support config option to the C API (#12630)

* (feat) Add gc_support config option within C API

* Restored 'gc' feature to wasmtime dependency

Removing the unconditional `gc` dependency requires additional guards so postponing that work.

Author: effulgentsia

crates/c-api/include/wasmtime/config.h

@@ -189,6 +189,14 @@ WASMTIME_CONFIG_PROP(void, wasm_function_references, bool)
  */
 WASMTIME_CONFIG_PROP(void, wasm_gc, bool)
 
+/**
+ * \brief Enables or disables GC support in Wasmtime entirely.
+ *
+ * This setting defaults to whether the `gc` feature was enabled at compile
+ * time.
+ */
+WASMTIME_CONFIG_PROP(void, gc_support, bool)
+
 /**
  * \brief Configures whether the WebAssembly SIMD proposal is
  * enabled.

crates/c-api/src/config.rs

@@ -107,6 +107,11 @@ pub extern "C" fn wasmtime_config_wasm_gc_set(c: &mut wasm_config_t, enable: boo
     c.config.wasm_gc(enable);
 }
 
+#[unsafe(no_mangle)]
+pub extern "C" fn wasmtime_config_gc_support_set(c: &mut wasm_config_t, enable: bool) {
+    c.config.gc_support(enable);
+}
+
 #[unsafe(no_mangle)]
 pub extern "C" fn wasmtime_config_wasm_simd_set(c: &mut wasm_config_t, enable: bool) {
     c.config.wasm_simd(enable);