[MCOMPILER-485] Always use forward slash for internal package name

Per JLS 4.2.1 if the file separator character is not a forward slash,
replace it

Author: dbwiddis

src/main/java/org/apache/maven/plugin/compiler/AbstractCompilerMojo.java

@@ -1363,12 +1363,16 @@ private void createMissingPackageInfoClasses( CompilerConfiguration compilerConf
     private byte[] generatePackage( CompilerConfiguration compilerConfiguration, String javaFile )
     {
         int version = getOpcode( compilerConfiguration );
+        String internalPackageName = javaFile.substring( 0, javaFile.length() - ".java".length() );
+        if ( File.separatorChar != '/' )
+        {
+            internalPackageName = internalPackageName.replace( File.separatorChar, '/' );
+        }
         ClassWriter cw = new ClassWriter( 0 );
         cw.visitSource( "package-info.java", null );
         cw.visit( version,
                 Opcodes.ACC_SYNTHETIC | Opcodes.ACC_ABSTRACT | Opcodes.ACC_INTERFACE,
-                javaFile.substring( 0, javaFile.length() - ".java".length() ),
-                null, "java/lang/Object", null );
+                internalPackageName, null, "java/lang/Object", null );
         return cw.toByteArray();
     }