rbd: do a few checks at build time
rbd: do a few checks at build time

This is a bit gratuitous, but there are a few things that can be
verified at build time rather than run time, so do that.

Signed-off-by: Alex Elder <f429030cf5c0faf36fac3d102073b6e63a647baa@dreamhost.com>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas