Update Lua package version requirement to Lua51

Author: shdwmtr

CMakeLists.txt

@@ -15,7 +15,7 @@ if(NOT CMAKE_BUILD_TYPE)
         FORCE)
 endif()
 
-find_package(Lua REQUIRED)
+find_package(Lua51 REQUIRED)
 include_directories(${LUA_INCLUDE_DIR})
 
 if(NOT USE_INTERNAL_FPCONV)