quote spaces in commands for Windows

See comments at:
    open-source-parsers@1a4dc3a

Author: cdunn2001

test/runjsontests.py

@@ -54,7 +54,7 @@ def runAllTests( jsontest_executable_path, input_dir = None,
         is_json_checker_test = (input_path in test_jsonchecker) or expect_failure
         print('TESTING:', input_path, end=' ')
         options = is_json_checker_test and '--json-checker' or ''
-        pipe = os.popen( "%s%s %s %s" % (
+        pipe = os.popen( '%s%s %s "%s"' % (
             valgrind_path, jsontest_executable_path, options,
             input_path) )
         process_output = pipe.read()