elf/dl-lookup.c: Use __glibc_likely and __glibc_unlikely

Convert all uses of __builtin_expect to __glibc_likely and
__glibc_unlikely. Most of these are trivial boolean expressions
but a few were not. In particular the use of __builtin_expect in
the switch expression in do_lookup_x has been removed. Verified
that there are no code changes on x86_64 and ARM aside from line
numbers.

ChangeLog:

2014-06-23  Will Newton  <will.newton@linaro.org>

	* elf/dl-lookup.c: Use __glibc_unlikely and __glibc_likely
	rather than __builtin_expect.