don't specify default-features = false for bindgen dependency

Per rust-lang/rust-bindgen#2030, this seems to interact poorly with other bindgen dependents that also specify `features = ["runtime"]` (and perhaps other dependents that don't specify `default-features = "false"` at all).

Author: mykmelez

Cargo.toml

@@ -13,7 +13,7 @@ repository = "https://github.com/nickray/littlefs2-sys"
 cty = "0.2.1"
 
 [build-dependencies]
-bindgen = { version = "0.56.0", default-features = false }
+bindgen = { version = "0.56.0" }
 cc = "1"
 
 [features]