Fixes to input-sys

First, the update_bindings feature should be plainly patched out since it tries to modify the sources (it tries to access the relative path src). Second, I'm not sure whether we should keep the gen feature, but if we do (and we can without issues since it only touches files in the target dir) then some whitelist_* functions must be renamed to allowlist_* due to the upgraded bindgen version (ref: https://github.com/rust-lang/rust-bindgen/pull/1990).

With these patches the remaining autopkgtests pass (at least on arm64), so you may want to remove the test_is_brokens if you have no other reason to keep them. Again, only tested on arm64.