make the node stdout flush workaround optional; fixes #2734

Author: kripken

src/postamble.js

@@ -174,6 +174,7 @@ function exit(status) {
   // exit the runtime
   exitRuntime();
 
+#if NODE_STDOUT_FLUSH_WORKAROUND
   if (ENVIRONMENT_IS_NODE) {
     // Work around a node.js bug where stdout buffer is not flushed at process exit:
     // Instead of process.exit() directly, wait for stdout flush event.
@@ -188,7 +189,9 @@ function exit(status) {
     setTimeout(function() {
       process['exit'](status);
     }, 500);
-  } else if (ENVIRONMENT_IS_SHELL && typeof quit === 'function') {
+  } else
+#endif
+  if (ENVIRONMENT_IS_SHELL && typeof quit === 'function') {
     quit(status);
   }
   // if we reach here, we must throw an exception to halt the current execution

src/settings.js

@@ -363,6 +363,9 @@ var NAMED_GLOBALS = 0; // If 1, we use global variables for globals. Otherwise
                        // they are referred to by a base plus an offset (called an indexed global),
                        // saving global variables but adding runtime overhead.
 
+var NODE_STDOUT_FLUSH_WORKAROUND = 1; // Whether or not to work around node issues with not flushing stdout. This
+                                      // can cause unnecessary whitespace to be printed.
+
 var EXPORTED_FUNCTIONS = ['_main', '_malloc'];
                                     // Functions that are explicitly exported. These functions are kept alive
                                     // through LLVM dead code elimination, and also made accessible outside of