build.rs: Manually pass the host to bindgen clang

In order to avoid errors like this when cross compiling:

    error: unknown target triple 'riscv32imc-unknown-none-elf', please use -triple or -arch

we pass the host target to clang instead of the target.

See rust-lang/rust-bindgen#1728 for the
upstream issue.

Signed-off-by: Alistair Francis <[email protected]>

build.rs

@@ -71,6 +71,7 @@ fn main() {
         .blocklist_function("qgcvt")
         .blocklist_function("strtold")
         .blocklist_type("_Float64x")
+        .clang_arg(format!("--target={}", env::var("HOST").unwrap()))
         .generate()
         .expect("Unable to generate bindings");