Log Message:
libretro-reicast: Update to 20181213

Changes:

* Use u32 for vertex indices to avoid overflow. Fix ggx15 coin chute issue
* Naomi: allow mapping P2 buttons onto P1. Fix coin chute issues.
* Clip high z vertices. Fixes bogus triangles in Soul Calibur intro and NHL 2K2 \ 
missing menu
* Unlock the emu thread if waiting for frame finish when loading state
* Use xxhash for palette hashing. extra depth scale for NHL 2K2
* Skip rendering is TA context is overrun. Fixes strip mode crash in FOTNS
* ARM dynarec: do a block check on the entire block.  Fixes Grandia II freezing \ 
on Now Loading... screen
* Backport Synchronous rendering option from upstream
* Fix some regions & add some missing keys
* Fix regions for Guilty Gear games
* Naomi: 7z archive and split/parent roms support
* rec-x64: don't reset the cycle counter for better scheduling
* Fix compile fail from math with conflicting types
* Naomi: fixes for vathlete, csmash, hotd2 and more
* Restrict regions for naomi games
* Add All GD Roms - Flyinghead FTW
* Naomi: GD-ROM support
* Naomi: improved JVS configuration. Ninja Assault
* Mushiking and Derby Additions/Fixes
* Fixes for wldkicks and wldkicksu
* Naomi/AW: Leverage libretro input descriptors to list and name each game's inputs
* Child and clone roms support for M1, M2/M3 and AW
* Naomi: allow bios selection with region core option
* Various fixes
* Parent rom support for M1, M2, M4 and AW
* Naomi/AW: avoid opposite DPad keys being pressed simultaneously
* AtomisWave roms support
* Naomi: support for M1 and M4 carts. BIOS version H supported.
* Naomi: add dual I/O boards / 4-player setup for Ring Out 4x4
* Naomi: M2 mame rom support
* CHD: swap bytes of CHDv5+ audio tracks
* Added 4:3 resolution for 4K screens
* CHD v5 and misc fixes
* Adding the 4:3 resolution of 1440x1080
* Maple: non-gamepad controls were ignored. Shikigami No Shiro II fix.
* Better rumble support. Fix rumble staying on all the time.