Reverting VLD1/VST1 base-updating/post-incrementing combining

This reverts patches 223862, 224198, 224203, and 224754, which were all
related to the vector load/store combining and were reverted/reaplied
a few times due to the same alignment problems we're seeing now.

Further tests, mainly self-hosting Clang, will be needed to reapply this
patch in the future.

llvm-svn: 228129