in aws-crt-sys/build.rs [112:120]
fn main() {
println!("cargo:rerun-if-changed=../src/api.h");
println!("cargo:rerun-if-env-changed=CC");
println!("cargo:rerun-if-env-changed=CFLAGS");
println!("cargo:rerun-if-env-changed=USE_OPENSSL");
compile_aws_crt_ffi();
generate_bindings();
}