Bring r264761 back with an extra fix.

The extra fix is to note that it still requires copy relocations.

Original message:

Change how we handle R_MIPS_LO16.

Mips aligns PT_LOAD to 16 bits (0x10000). That means that the lower 16
bits are always the same, so we can, effectively, say that the
relocation is relative.

P.S.: Suggestions for a better name for the predicate are welcome :-)

llvm-svn: 265150