Libretro core - Support Mouse input

[Mimigris]

Player platform:

Windows, 64 bits continuous core of the Player.

Describe the issue in detail and how to reproduce it:

When a mouse input is called on this platform, a warning message stating that mouse input is not supported on this platform is displayed and will make the feature not work.

This platform should normally be able to support mouse input, seeing that some other snes emulators working as cores are compatible with a mouse for reference, so this feature could normally be supported on this platform in the future.