Skip wasmBinaryFile initialization on pthread workers

The fact that we were calling `locateFile` in an attempt to find the
wasm binary on each worker was confusing at best.  The wasm file is
always received via postMessage when running on the worker.

See #21826 and #21827

Author: sbc100

src/preamble.js

@@ -596,6 +596,12 @@ function instrumentWasmTableWithAbort() {
 }
 #endif
 
+#if PTHREADS
+// We only need to locate the wasm binary on the main thread.  Worker threads
+// receive the wasm module via postMessage instead.
+if (!ENVIRONMENT_IS_PTHREAD) {
+#endif
+
 var wasmBinaryFile;
 #if EXPORT_ES6 && USE_ES6_IMPORT_META && !SINGLE_FILE && !AUDIO_WORKLET
 if (Module['locateFile']) {
@@ -618,6 +624,10 @@ if (Module['locateFile']) {
 }
 #endif
 
+#if PTHREADS
+}
+#endif
+
 function getBinarySync(file) {
   if (file == wasmBinaryFile && wasmBinary) {
     return new Uint8Array(wasmBinary);

test/other/metadce/test_metadce_minimal_pthreads.gzsize

@@ -1 +1 @@
-5253
+5257

test/other/metadce/test_metadce_minimal_pthreads.jssize

@@ -1 +1 @@
-11457
+11469