Log message:
Add SHA512 digests for distfiles for emulators category

Problems found with existing digests:
	Package suse131_libSDL
	1c4d17a53bece6243cb3e6dd11c36d50f851a4f4 [recorded]
	da39a3ee5e6b4b0d3255bfef95601890afd80709 [calculated]
	Package suse131_libdbus
	de99fcfa8e2c7ced28caf38c24d217d6037aaa56 [recorded]
	da39a3ee5e6b4b0d3255bfef95601890afd80709 [calculated]
	Package suse131_qt4
	94daff738912c96ed8878ce1a131cd49fb379206 [recorded]
	886206018431aee9f8a01e1fb7e46973e8dca9d9 [calculated]

Problems found locating distfiles for atari800, compat12, compat 13,
compat14, compat15, compat20, compat30, compat40, compat50,
compat50-x11, compat51, compat51-x11, compat60, compat61,
compat61-x11, fmsx, osf1_lib, vice, xbeeb, xm7.

Otherwise, existing SHA1 digests verified and found to be the same on
the machine holding the existing distfiles (morden).  All existing
SHA1 digests retained for now as an audit trail.

Log message:
Import libretro-stella-20150205 as emulators/libretro-stella.

Libretro is a simple but powerful development interface that allows for the
easy creation of emulators, games and multimedia applications that can plug
straight into any libretro-compatible frontend. This development interface is
open to others so that they can run these pluggable emulator and game cores
also in their own programs or devices.

Stella is an Atari 2600 video game system emulator.