Fix list_files on Windows and clear GRAAL_PYTHON_ARGS in graalpy.cmd

(cherry picked from commit d2473b5)

Author: otethal

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/GraalPythonModuleBuiltins.java

@@ -1053,7 +1053,7 @@ private static Set<String> list(TruffleFile dir, TruffleFile rd) throws IOExcept
             // add dir
             TruffleFile rootDir = rd == null ? dir : rd;
             String rootPath = makeDirPath(rootDir.getAbsoluteFile().getPath());
-            int rootEndIdx = rootPath.lastIndexOf("/", rootPath.lastIndexOf("/") - 1);
+            int rootEndIdx = rootPath.lastIndexOf(File.separator, rootPath.lastIndexOf(File.separator) - 1);
             ret.add(dirPath.substring(rootEndIdx));
 
             // add parents up to root
@@ -1079,8 +1079,8 @@ private static Set<String> list(TruffleFile dir, TruffleFile rd) throws IOExcept
         }
 
         private static String makeDirPath(String p) {
-            if (!p.endsWith("/")) {
-                p = p + "/";
+            if (!p.endsWith(File.separator)) {
+                p = p + File.separator;
             }
             return p;
         }

graalpython/lib-graalpython/modules/standalone/app/graalpy.cmd

@@ -14,6 +14,7 @@ for /f "delims=" %%i in ('%JAVA% VTabCreator.java') do set VTAB=%%i
 del VTabCreator.java
 
 REM Store each argument separated by vtab
+set GRAAL_PYTHON_ARGS=
 :loop
 set GRAAL_PYTHON_ARGS=%GRAAL_PYTHON_ARGS%%VTAB%%~1
 shift /1