suppress warnings: unknown edition and unexpected cfg (#1471)

Cargo.toml

@@ -10,6 +10,7 @@ keywords = ["SDL", "windowing", "graphics", "api", "engine"]
 categories = ["rendering","api-bindings","game-engines","multimedia"]
 readme = "README.md"
 resolver = "2"
+edition = "2015"
 
 [lib]
 name = "sdl2"

sdl2-sys/Cargo.toml

@@ -57,3 +57,6 @@ mixer = []
 image = []
 ttf = []
 gfx = []
+
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(mac_framework)','cfg(ios_framework)'] }