feat(c-api) Shrink vector of traps.

Ensure that the size of the vector of the instance's traps equals its
capacity by shrinking it.

lib/c-api/src/wasm_c_api/instance.rs

@@ -45,6 +45,7 @@ pub unsafe extern "C" fn wasm_instance_new(
                 let trap: Box<wasm_trap_t> = Box::new(runtime_error.into());
                 let mut traps: Vec<*mut wasm_trap_t> = Vec::with_capacity(1);
                 traps.push(Box::into_raw(trap));
+                traps.shrink_to_fit();
 
                 let pointer = traps.as_mut_ptr();
                 mem::forget(traps);