disable some features when in hardcore mode

[meleu]

IMO this is one of the most (if not THE most) important issue to solve before spreading the word about RALibretro:

disable the following features when in hardcore mode:

• frame-by-frame
• load/save state

[meleu]

Tested latest builds (04/february/2018):

• pause emulation and frame-by-frame feature doesn't work on hardcore mode. Done! Solved! 👍
• load/save state. It still works when in hardcore mode.

[leiradel]

Fixed in https://github.com/leiradel/RASuite/commit/9683b3fbc13951bc05954063657fec0da5bb4d37