Revert "use another xcode"

This reverts commit fe9d6599.

.travis.yml

@@ -4,7 +4,7 @@ os:
 - osx
 sudo: required
 dist: xenial
-osx_image: xcode10
+osx_image: xcode8
 addons:
   ssh_known_hosts:
   - github.com

premake5.lua

@@ -24,7 +24,7 @@ solution "ygo"
         libdirs { "/usr/local/lib" }
 
     configuration "macosx"
-        defines { "LUA_USE_MACOSX" }
+        defines { "LUA_USE_MACOSX", "DBL_MAX_10_EXP=+308" }
         includedirs { "/usr/local/include", "/usr/local/include/*" }
         libdirs { "/usr/local/lib", "/usr/X11/lib" }
         buildoptions { "-stdlib=libc++" }