Remove errors on ancient EMMAKEN environment variables (emscripten-core#27452)

While working on emscripten-core#27401 these seems like errors that were not worth
reproducing in the native launcher.

Author: sbc100

emcc.py

@@ -306,16 +306,6 @@ def main(args):
       print(libname)
     return 0
 
-  if 'EMMAKEN_NO_SDK' in os.environ:
-    exit_with_error('EMMAKEN_NO_SDK is no longer supported.  The standard -nostdlib and -nostdinc flags should be used instead')
-
-  if 'EMMAKEN_COMPILER' in os.environ:
-    exit_with_error('`EMMAKEN_COMPILER` is no longer supported.\n' +
-                    'Please use the `LLVM_ROOT` and/or `COMPILER_WRAPPER` config settings instead')
-
-  if 'EMMAKEN_CFLAGS' in os.environ:
-    exit_with_error('`EMMAKEN_CFLAGS` is no longer supported, please use `EMCC_CFLAGS` instead')
-
   if 'EMCC_REPRODUCE' in os.environ:
     options.reproduce = os.environ['EMCC_REPRODUCE']
 

test/test_other.py

@@ -12451,14 +12451,6 @@ def test_missing_malloc_export(self):
   def test_getrusage(self):
     self.do_other_test('test_getrusage.c')
 
-  @with_env_modify({'EMMAKEN_COMPILER': shared.CLANG_CC})
-  def test_emmaken_compiler(self):
-    self.assert_fail([EMCC, '-c', test_file('core/test_hello_world.c')], 'emcc: error: `EMMAKEN_COMPILER` is no longer supported')
-
-  @with_env_modify({'EMMAKEN_CFLAGS': '-O2'})
-  def test_emmaken_cflags(self):
-    self.assert_fail([EMCC, '-c', test_file('core/test_hello_world.c')], 'emcc: error: `EMMAKEN_CFLAGS` is no longer supported')
-
   @no_windows('relies on a shell script')
   def test_compiler_wrapper(self):
     create_file('wrapper.sh', '''\
@@ -13045,10 +13037,6 @@ def test_missing_symbols_at_runtime(self, args):
                  cflags=['-sWARN_ON_UNDEFINED_SYMBOLS=0', '-sAUTO_JS_LIBRARIES=0'] + args,
                  assert_returncode=NON_ZERO)
 
-  @with_env_modify({'EMMAKEN_NO_SDK': '1'})
-  def test_EMMAKEN_NO_SDK(self):
-    self.assert_fail([EMCC, test_file('hello_world.c')], 'emcc: error: EMMAKEN_NO_SDK is no longer supported')
-
   @parameterized({
     'default': ('', '2147483648'),
     '1GB': ('-sMAXIMUM_MEMORY=1GB', '1073741824'),