Remove the ffi-headers feature

Rely on a separate cbindgen instance instead, which is less self-contained but more practical.

ffi/Cargo.toml

@@ -3,7 +3,6 @@ name = "loot-condition-interpreter-ffi"
 version = "3.1.0"
 authors = ["Oliver Hamlet <oliver@ortham.io>"]
 license = "MIT"
-build = "build.rs"
 edition = "2018"
 
 [dependencies]
@@ -13,10 +12,3 @@ libc = "0.2"
 [lib]
 name = "loot_condition_interpreter_ffi"
 crate-type = ["staticlib"]
-
-[features]
-default = []
-ffi-headers = ["cbindgen"]
-
-[build-dependencies]
-cbindgen = { version = "0.26", optional = true }

ffi/build.rs

@@ -1,25 +0,0 @@
-#[cfg(feature = "ffi-headers")]
-mod ffi_headers {
-    extern crate cbindgen;
-
-    use std::env;
-    use std::fs;
-
-    use self::cbindgen::generate;
-
-    pub fn generate_headers() {
-        let crate_dir = env::var("CARGO_MANIFEST_DIR")
-            .expect("could not get value of CARGO_MANIFEST_DIR env var");
-
-        fs::create_dir_all("include").expect("could not create include directory");
-
-        generate(&crate_dir)
-            .expect("could not generate C/C++ header file")
-            .write_to_file("include/loot_condition_interpreter.h");
-    }
-}
-
-fn main() {
-    #[cfg(feature = "ffi-headers")]
-    ffi_headers::generate_headers();
-}