Add LUA_USE_C89 for Dreamcast to avoid POSIX calls in Lua

KOS newlib does not support popen, system, or tmpfile. Without
LUA_USE_C89, Lua's os library tries to register wrappers for these
functions, which can leave the os table nil and crash with
"attempt to index a nil value" during sandbox creation.

Signed-off-by: Panagiotis Georgiadis <pgeorgia@redhat.com>

Author: drpaneas

3rdParty/Lua/CMakeLists.txt

@@ -30,7 +30,7 @@ elseif(TARGET_PLATFORM STREQUAL "dos")
   target_compile_definitions(lua_static PUBLIC -DLUA_USE_C89)
 elseif(ANDROID AND ("${ANDROID_ABI}" STREQUAL "armeabi-v7a" OR "${ANDROID_ABI}" STREQUAL "x86"))
   target_compile_definitions(lua_static PUBLIC -DLUA_USE_C89)
-elseif(NINTENDO_3DS OR VITA OR NINTENDO_SWITCH OR NXDK)
+elseif(NINTENDO_3DS OR VITA OR NINTENDO_SWITCH OR NXDK OR DREAMCAST)
   target_compile_definitions(lua_static PUBLIC -DLUA_USE_C89)
 elseif(IOS)
   target_compile_definitions(lua_static PUBLIC -DLUA_USE_IOS)