Fix broken ndk version caching (HaxeFoundation#1204)

This function would just store the version of the last checked ndk path,
so it would return the wrong value if this is not the same ndk path that
was last checked.

It now only reuses the version value if the path was the same.

Author: tobil4sk

tools/hxcpp/Setup.hx

@@ -125,11 +125,14 @@ class Setup
    }
 
    static var gotNdkVersion = 0.0;
+   static var cachedNdkPath:Null<String> = null;
    static public function getNdkVersion(inDirName:String, newStyle=false):Float
    {
-      if (gotNdkVersion!=0)
+      if (gotNdkVersion!=0 && cachedNdkPath==inDirName)
          return gotNdkVersion;
 
+      cachedNdkPath = inDirName;
+
       Log.v("Try to get version from source.properties");
       var src = toPath(inDirName+"/source.properties");
       if (sys.FileSystem.exists(src))