Remove lld/Core/range.h.

IIUC, range was an experiment to see how N3350 would work in LLD.
It turned out it didn't get traction, and it is basically duplicate
of iterator_range in ADT. We have only two occurrences of range,
and all of them are easily rewritten without it.

http://reviews.llvm.org/D17687

llvm-svn: 262171