Rename __unused to __UNUSED for glibc support.

Glibc declares unused fields as __unused and so a #define for __unused causes
issues when we built against glibc on the host. Rename __unused to __UNUSED as
a workaround.
This fixed checkbuild for 64-bit host builds. Bug: 13751317

Change-Id: Ic2cd52518c16661497cc819cb3fd7f1fa5c6f0fb
1 file changed