Fix constant folding for one lane vector types. Constant folding one lane vector types not returns a vector instead of a scalar.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180254 91177308-0d34-0410-b5e6-96231b3b80d8
Clarify getRelocationAddress x getRelocationOffset a bit.

getRelocationAddress is for dynamic libraries and executables,
getRelocationOffset for relocatable objects.

Mark the getRelocationAddress of COFF and MachO as not implemented yet. Add a
test of ELF's. llvm-readobj -r now prints the same values as readelf -r.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180259 91177308-0d34-0410-b5e6-96231b3b80d8
Use a pointer as the relocation iterator.

Since the relocation iterator walks only the relocations in one section, we
can just use a pointer and avoid fetching information about the section at
every reference.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180262 91177308-0d34-0410-b5e6-96231b3b80d8