Fix to compile for windows

This change includes a workaround for dirent.h on windows not
including d_type.

Change-Id: Ieaa3f298d2e6b32f2d8367384a1d02a2f5d06cca
diff --git a/tools/aapt/FileFinder.h b/tools/aapt/FileFinder.h
index 3f87aba..6974aee 100644
--- a/tools/aapt/FileFinder.h
+++ b/tools/aapt/FileFinder.h
@@ -25,6 +25,8 @@
     virtual bool findFiles(String8 basePath, Vector<String8>& extensions,
                            KeyedVector<String8,time_t>& fileStore,
                            DirectoryWalker* dw) = 0;
+
+    virtual ~FileFinder() {};
 };
 
 class SystemFileFinder : public FileFinder {