Build libinputflinger for host

We don't have a usecase for it today, but the main motivation here is to
unify the target and host build parameters.

Also, this exposed an issue where ::write wasn't wrapped.

The host build produced an error:
frameworks/native/services/inputflinger/InputManager.cpp:189:5: error: ignoring return value of function declared with 'warn_unused_result' attribute [-Werror,-Wunused-result]
    ::write(fd, dump.c_str(), dump.size());

Bug: 271455682
Test: m libinputflinger
Change-Id: If1abc85b230f8e928422dab4c6bb33834b6393ee