Fix crashes in IRCE caused by mismatched types

There are places where the inductive range check elimination pass
depends on two llvm::Values or llvm::SCEVs to be of the same
llvm::Type when they do not need to be. This patch relaxes those
restrictions (by bailing out of the optimization if the types
mismatch), and adds test cases to trigger those paths.

These issues were found by bootstrapping clang with IRCE running in
the -O3 pass ordering.

Differential Revision: http://reviews.llvm.org/D7082

llvm-svn: 226793