Log Message:
libretro-gambatte: Update to 20200207

Changes:
          * Add optional LCD ghosting effect –
            This backports the LCD ghosting effects that were recently added
            to mGBA

            It replaces the existing Mix Frames core option with Interframe
            Blending. The old Accurate and Fast frame mixing settings have
            been renamed to Simple (Accurate) and Simple (Fast) – these
            perform the same 50:50 mix of the current and previous frames as
            before, required to achieve correct rendering of games that rely
            on LCD ghosting for transparency effects.

            In addition to these settings, there are now LCD Ghosting
            (Accurate) and LCD Ghosting (Fast) options. The former recreates
            the LCD response effect of RetroArch’s Gameboy Shader. The latter
            is similar, but uses a single accumulation buffer – which is more
            efficient, but lacks the subtlety of the shader implementation.

            Here are some stats showing the typical increase in performance
            overheads when using the various methods:

            Simple (Accurate): 30%
            Simple (Fast): 13%
            LCD Ghosting (Accurate): 48%
            LCD Ghosting (Fast): 28%
          * Do not add pointers to memory map if they are not available –

            skips sram when no sram is available
            skips extra RAM banks if not running in GBC mode
          * tvOS support