error on undefined symbols in js configure-ing

emcc

@@ -557,6 +557,7 @@ if CONFIGURE_CONFIG or CMAKE_CONFIG:
 
   cmd = [compiler] + list(filter_emscripten_options(sys.argv[1:]))
   if not use_js: cmd += shared.EMSDK_OPTS + ['-DEMSCRIPTEN']
+  if use_js: cmd += ['-s', 'ERROR_ON_UNDEFINED_SYMBOLS=1'] # configure tests should fail when an undefined symbol exists
 
   if DEBUG: print >> sys.stderr, 'emcc, just configuring: ', ' '.join(cmd)
   if debug_configure: open(tempout, 'a').write('emcc, just configuring: ' + ' '.join(cmd) + '\n\n')