Revert "Revert "Fix alignment bug in COFF emission.""

This revert was done so that my other patch to add test framework could
land separately.  Now the revert can be reverted and this patch can
reland.

This reverts commit 18b3c75b2b0d32601fb60a06b9672c33d6f0dff9.

llvm-svn: 305259