Fix posix_memalign introduced tag.

Apparently this didn't make it to all android-16 devices. As far as
we know it did make it for all android-17 devices.

Test: make checkbuild
Bug: https://github.com/android-ndk/ndk/issues/647
Change-Id: I2f07cfb1254e2a203c1c10b91b0be46bf37ea853