Avoid calling writeStackCookie to early in worker.js

When running a worker we don't want to write the stack cookie until the
worker is actually running a pthread.  This is done in
`establishStackSpace`.

For this reason we don't want to run `writeStackCookie` during
`run` (which is used only to initiialize the worker, before its
running a thread).

Author: sbc100

src/postamble.js

@@ -239,10 +239,6 @@ function run(args) {
     return;
   }
 
-#if STACK_OVERFLOW_CHECK
-  stackCheckInit();
-#endif
-
 #if RELOCATABLE
   if (!dylibsLoaded) {
   // Loading of dynamic libraries needs to happen on each thread, so we can't
@@ -287,6 +283,10 @@ function run(args) {
   }
 #endif
 
+#if STACK_OVERFLOW_CHECK
+  stackCheckInit();
+#endif
+
   preRun();
 
   // a preRun added a dependency, run will be called later

src/preamble.js

@@ -375,9 +375,6 @@ function preRun() {
 }
 
 function initRuntime() {
-#if STACK_OVERFLOW_CHECK
-  checkStackCookie();
-#endif
 #if ASSERTIONS
   assert(!runtimeInitialized);
 #endif
@@ -396,6 +393,9 @@ function initRuntime() {
   err('__set_stack_limits: ' + _emscripten_stack_get_base() + ', ' + _emscripten_stack_get_end());
 #endif
   ___set_stack_limits(_emscripten_stack_get_base(), _emscripten_stack_get_end());
+#endif
+#if STACK_OVERFLOW_CHECK
+  checkStackCookie();
 #endif
   <<< ATINITS >>>
   callRuntimeCallbacks(__ATINIT__);