fixed Memory leak when opening PDF as a byte array

[ViktorSkabiak]

This is the fix for the issue #84 You can find examples before and after the fix in the issue description.

Please check the pull request, provide your thoughts and merge it if you consider it valuable. I saw a lot of people complaining about memory usage, so this fix will be useful.

In case of any questions please contact me. Thanks in advance

[ViktorSkabiak]

@barteksc @AhmerAfzal1

[AhmerAfzal1]

@barteksc @AhmerAfzal1

Good

[johngray1965]

@ViktorSkabiak if you want to submit a PR against mine, I'll merge it.

https://github.com/johngray1965/PdfiumAndroidKt