fix xmake build

Author: jube

xmake.lua

@@ -66,7 +66,7 @@ target("gf0")
     add_includedirs("include-priv")
     add_includedirs("$(buildir)/config")
     add_includedirs("library/vendor/glad/gles20/include")
-    add_packages("opengl-headers", "libsdl", "freetype", "pugixml")
+    add_packages("opengl-headers", "libsdl2", "freetype", "pugixml")
     add_deps("gfcore0")
     add_rpathdirs("$ORIGIN")
     set_license("Zlib")