Fix lsan false positive in emscripten_malloc_wasm_worker. NFC (#19520)

This function never frees is memory so we don't want to consider
the memory allocated here a memory leak.  This fixes a failure of the
`asan.test_wasm_worker_hello` test which started failing after the
recent compiler-rt update in #19506.

Author: sbc100

.circleci/config.yml

@@ -469,6 +469,7 @@ jobs:
             asan.test_dlfcn_basic
             asan.test_async_hello_stack_switching
             asan.test_cubescript
+            asan.test_wasm_worker_hello
             lsan.test_stdio_locking
             lsan.test_dlfcn_basic
             lsan.test_pthread_create"

system/lib/wasm_worker/library_wasm_worker.c

@@ -57,7 +57,7 @@ emscripten_wasm_worker_t emscripten_malloc_wasm_worker(size_t stackSize)
 	// Add the TLS size to the provided stackSize so that the allocation
 	// will always be large enough to hold the worker TLS data.
 	stackSize += ROUND_UP(__builtin_wasm_tls_size(), 16);
-	return emscripten_create_wasm_worker(memalign(16, stackSize), stackSize);
+	return emscripten_create_wasm_worker(emscripten_builtin_memalign(16, stackSize), stackSize);
 }
 
 void emscripten_wasm_worker_sleep(int64_t nsecs)