[Lua/Cmake] Prefer LuaJIT over normal Lua (#1235)

* Add a separate FindLuaJit.cmake

* Remove LuaJit from our modified FindLua51.cmake

* Make use of the new FindLuaJit

The reason for splitting them up like this is so we can have a
preference for LuaJIT that's not determined by the search order in
FindLua51.cmake as well as giving the server operators the choice to
prefer normal Lua with the EQEMU_PREFER_LUA cmake option

CMakeLists.txt

@@ -55,6 +55,7 @@ FIND_PACKAGE(MariaDB)
 FIND_PACKAGE(ZLIB)
 FIND_PACKAGE(OpenSSL)
 FIND_PACKAGE(Lua51)
+FIND_PACKAGE(LuaJit)
 FIND_PACKAGE(PerlLibs)
 FIND_PACKAGE(Sodium)
 FIND_PACKAGE(mbedTLS)
@@ -87,6 +88,12 @@ ELSE()
 	MESSAGE(STATUS "* Lua:                                   MISSING *")
 ENDIF()
 
+IF(LuaJit_FOUND)
+	MESSAGE(STATUS "* LuaJIT:                                  FOUND *")
+ELSE()
+	MESSAGE(STATUS "* LuaJIT:                                MISSING *")
+ENDIF()
+
 IF(PerlLibs_FOUND)
 	MESSAGE(STATUS "* Perl:                                    FOUND *")
 ELSE()
@@ -122,6 +129,7 @@ OPTION(EQEMU_BUILD_LOGIN "Build the login server." ON)
 OPTION(EQEMU_BUILD_HC "Build the headless client." OFF)
 OPTION(EQEMU_BUILD_TESTS "Build utility tests." OFF)
 OPTION(EQEMU_BUILD_CLIENT_FILES "Build Client Import/Export Data Programs." ON)
+OPTION(EQEMU_PREFER_LUA "Build with normal Lua even if LuaJIT is found." OFF)
 
 IF(EQEMU_COMMANDS_LOGGING)
 	ADD_DEFINITIONS(-DCOMMANDS_LOGGING)
@@ -212,7 +220,12 @@ ELSE()
 	SET(SODIUM_LIBRARY_ENABLED OFF)
 ENDIF()
 
-IF(Lua51_FOUND)
+IF(LUAJIT_FOUND AND NOT (EQEMU_PREFER_LUA AND Lua51_FOUND))
+	SET(LUA_LIBRARY_TYPE "  LuaJIT")
+	SET(LUA_LIBRARY_ENABLED ON)
+	SET(LUA_LIBRARY_LIBS ${LUAJIT_LIBRARY} luabind)
+	SET(LUA_LIBRARY_INCLUDE ${LUAJIT_INCLUDE_DIR} "${CMAKE_CURRENT_SOURCE_DIR}/libs/luabind")
+ELSEIF(Lua51_FOUND )
 	SET(LUA_LIBRARY_TYPE " Lua 5.1")
 	SET(LUA_LIBRARY_ENABLED ON)
 	SET(LUA_LIBRARY_LIBS ${LUA_LIBRARY} luabind)