API: libcrmcommon: deprecate builtin_expect(), likely(), and __unlikely()

Pacemaker's public API should be Pacemaker-specific, and not provide
general-purpose features like compiler hinting macros. (The naming suggests
these were intended to be internal to begin with, anyway.)

The use of these internally has been removed, since everything I've read
suggests that these gcc-specific hints have no benefit in most cases. Modern
CPUs' run-time dynamic branch prediction is generally better than a compiler's
even with hints, and when the compiler is better it's generally by nanoseconds.