[ConstantFolding, InstSimplify] Handle more vector GEPs
This patch addresses some additional cases where the compiler crashes
upon encountering vector GEPs. This should fix PR36116.
Differential Revision: https://reviews.llvm.org/D44219
Reference: https://bugs.llvm.org/show_bug.cgi?id=36116
This fixes an assertion when building the emulators/snes9x port.
Reported by: jbeich
PR: 225471
MFC after: 3 months
X-MFC-With: r327952