LoopVectorize: Vectorize all accesses in address space zero with unit stride

We can vectorize them because in the case where we wrap in the address space the
unvectorized code would have had to access a pointer value of zero which is
undefined behavior in address space zero according to the LLVM IR semantics.
(Thank you Duncan, for pointing this out to me).

Fixes PR16592.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186088 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a FIXME about the format and add a test.

While at it, use strftime on Unix too and use the thread safe versions
of localtime.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186090 91177308-0d34-0410-b5e6-96231b3b80d8
Use move semantics if possible to construct ConstantRanges.

Arithmetic on ConstantRanges creates a lot of large temporary APInts that
benefit from move semantics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186091 91177308-0d34-0410-b5e6-96231b3b80d8
Looks like some versions of mingw don't have errno_t. Use int.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186092 91177308-0d34-0410-b5e6-96231b3b80d8
InsertBefore is the same as AddBefore. Delete it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186094 91177308-0d34-0410-b5e6-96231b3b80d8