<sys/ioctl.h> shouldn't pollute the namespace as much.

The history has no motivation for <asm/termbits.h>, and other C libraries
don't seem to include any of the extra types and constants that gains us.

This caused problems building FFMPEG, which defines its own B0.

Bug: https://github.com/android-ndk/ndk/issues/630
Test: builds
Change-Id: If032b9fa7860777c13f7bd8e68fb78ff606dcd94