android save picker, create dir api wip

src/asset.cpp

@@ -9,6 +9,7 @@
 #ifdef __ANDROID__
 #include <dirent.h>
 AAssetManager* Asset::m_am;
+bool android_create_dir(const std::string& path);
 #endif
 
 bool Asset::delete_file(const std::string& path)
@@ -134,6 +135,15 @@ bool Asset::is_asset(const std::string & path)
     return path.substr(0, 5) == "data/";
 }
 
+bool Asset::create_dir(const std::string& path)
+{
+#if __WIN__
+    return PathFileExistsA(path.c_str()) ? true : CreateDirectoryA(path.c_str(), NULL);
+#elif __ANDROID__
+    return android_create_dir(path);
+#endif
+}
+
 bool Asset::open(const char* path)
 {
     //LOG("Asset::open %s", path);