fix: lay out RetroPie standalone packages

RetroPie's YAML listed no standalone_cores, so every package was laid
out as a libretro core and the standalone files of amiberry, dolphin,
hatari, mame and ppsspp never reached the pack. Packages without the
lr- prefix (bar the retroarch frontend) are now standalone, and names
shipped both ways are dual-mode.

platforms/retropie.yml

@@ -186,6 +186,132 @@ cores:
 - yabause
 - yquake2
 - zesarux
+standalone_cores:
+- advmame
+- advmame-0.94
+- advmame-1.4
+- ags
+- alephone
+- amiberry
+- atari800
+- basilisk
+- cannonball
+- capricerpi
+- cdogs-sdl
+- cgenius
+- coolcv
+- daphne
+- darkplaces-quake
+- dgen
+- dolphin
+- dosbox
+- dosbox-sdl2
+- dosbox-staging
+- drastic
+- dsda-doom
+- dxx-rebirth
+- eduke32
+- fbzx
+- flycast
+- frotz
+- fs-uae
+- fuse
+- gemrb
+- giana
+- gngeopi
+- gpsp
+- gzdoom
+- hatari
+- hypseus
+- ionfury
+- ioquake3
+- jumpnbump
+- jzintv
+- kodi
+- linapple
+- lincity-ng
+- love
+- love-0.10.2
+- lzdoom
+- mame
+- mame4all
+- micropolis
+- minecraft
+- minivmac
+- mupen64plus
+- mysticmine
+- np2pi
+- openblok
+- openbor
+- openmsx
+- openpht
+- openttd
+- opentyrian
+- oricutron
+- osmose
+- pcsx-rearmed
+- pcsx2
+- pifba
+- pisnes
+- ppsspp
+- ppsspp-1.5.4
+- px68k
+- quake3
+- quasi88
+- redream
+- reicast
+- rpix86
+- scummvm
+- scummvm-sdl1
+- sdlpop
+- sdltrs
+- simcoupe
+- smw
+- snes9x
+- solarus
+- splitwolf
+- srb2
+- steamlink
+- stella
+- stratagus
+- supermodel3
+- supertux
+- ti99sim
+- ti99sim-sdl1
+- tyrquake
+- uae4all
+- uae4arm
+- uqm
+- vice
+- vvvvvv
+- wolf4sdl
+- xm7
+- xrick
+- xroar
+- yabasanshiro
+- yquake2
+- zesarux
+dual_mode_cores:
+- atari800
+- dolphin
+- dosbox
+- flycast
+- fuse
+- gpsp
+- hatari
+- mame
+- mupen64plus
+- pcsx-rearmed
+- ppsspp
+- px68k
+- quasi88
+- scummvm
+- snes9x
+- stella
+- tyrquake
+- uae4arm
+- vice
+- xrick
 launchers:
 - emulator: advmame-0.94
   package: advmame-0.94