Fix path separator and disable polyglot_app test on Windows

(cherry picked from commit 02e6319)

Author: otethal

graalpython/com.oracle.graal.python.test/src/tests/test_standalone.py

@@ -42,6 +42,7 @@
 import tempfile
 import unittest
 import shutil
+import sys
 
 is_enabled = 'ENABLE_STANDALONE_UNITTESTS' in os.environ and os.environ['ENABLE_STANDALONE_UNITTESTS'] == "true"
 MVN_CMD = [shutil.which('mvn')]
@@ -96,6 +97,7 @@ def get_gp():
     return graalpy
 
 @unittest.skipUnless(is_enabled, "ENABLE_STANDALONE_UNITTESTS is not true")
+@unittest.skipUnless(sys.platform != 'win32', 'not supported on Windows')
 def test_polyglot_app():
 
     graalpy = get_gp()

graalpython/lib-graalpython/modules/standalone/__main__.py

@@ -473,7 +473,7 @@ def build_binary(self, ni, jc):
                 print(p.stderr.decode())
                 exit(1)
 
-            ni_modules = ":".join([os.path.join(self.modules_path, f) for f in os.listdir(self.modules_path) if f.endswith(".jar")] + [self.target_dir])
+            ni_modules = os.pathsep.join([os.path.join(self.modules_path, f) for f in os.listdir(self.modules_path) if f.endswith(".jar")] + [self.target_dir])
             cmd = [ni, "--module-path", ni_modules] + self.parsed_args.ni_args[:]
 
             if self.parsed_args.Os: