Don't pass RUSTFLAGS to the invocation of binding-generator

It's meant to be only applied to the final artifacts, so it's problematic during cross-compile: rust-lang/cargo#4423

Author: twistedfall

CHANGES.md

@@ -1,3 +1,6 @@
+* 0.81.2
+  * Fix building when crosscompiling with target-specific RUSTFLAGS
+
 * 0.81.1
   * Fix building on macOS (fixes https://github.com/twistedfall/opencv-rust/issues/460)
 

build.rs

@@ -290,7 +290,8 @@ fn build_clang_generator() -> io::Result<Child> {
 			"--bin",
 			"binding-generator",
 		])
-		.env("CARGO_TARGET_DIR", &*OUT_DIR);
+		.env("CARGO_TARGET_DIR", &*OUT_DIR)
+		.env_remove("CARGO_ENCODED_RUSTFLAGS"); // RUSTFLAGS are meant to affect final build artifacts only
 	if let Some(host_triple) = HOST_TRIPLE.as_ref() {
 		cargo.args(["--target", host_triple]);
 	}