Update slang for LLVM 3.4 rebase.

Remove LinkOnceODRAutoHideLinkage, since it is now just a special case of
LinkOnceODRLinkage.

Remove CaseRange expansion code from all bitcode writers, since it is now dead.

Fix up HeaderSearch constructor.

Change-Id: I38547486be509b16ea5d8218b43c31ae35b37d3b
7 files changed