Updated libjpeg to Version 9c (25 Jun 2018)

[znvjder]

This version of libjpeg contains numerous improvements in security, performance and stability.
From request @Dutchman101

Available on github: https://github.com/winlibs/libjpeg (last update 25 Jan 2018)
Source: https://www.ijg.org/ (last update 14 Jan 2018)

[jushar]

Thanks for the patch, but for security reasons, we do not accept vendor library patches from non-maintainers (as we can't verify them).

[znvjder]

For security reasons: i used on my pull request files from the original and verified source - https://ijg.org/

I mentioned a link to github winlibs in the comment, only because of the improved versions of win32.bat and cmake for compilation and checking.

but as you like. :)
regards!