An aligned constant pool entry may require extra alignment padding where
the new water is created. Take that into account when computing offset.
Also consider the alignment of other constant pool entries when
splitting a basic block. Alignment padding may make it necessary to
move the split point higher.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146609 91177308-0d34-0410-b5e6-96231b3b80d8