We don't list most of bionic on dac since it would be overwhelming for
the current layout, but this file in particular seems useful,
especially __ANDROID_API__. Unfortunately, c2devsite doesn't include
macro documentation. Until then, it's still useful to include the
functions defined in this header.
I've also elaborated a bit in the __ANDROID_API__ documentation, since
the existing phrasing led to confusion over whether it was closer to
minSdkVersion or compileSdkVersion. In practice these are identical
for the NDK, but if we switch to weakly-linked APIs via the
availability attribute that would change.
Test: built docs, looked at them
Bug: None
Change-Id: I5cf78a6143b5c15790c369bdf888611e4c1189db
d8f46916b6