[llgo] Fix `debug` to use latest `DIBuilder` bindings

Two recent commits to the LLVM Go bindings caused breaking changes
to llgo:

  1. r284707 - Moving the `AlignInBits` field from `DIBasicType` to
               `DIAutoVariable`.

  2. r284482 - The `AlignInBits` fields going from `uint64` to `uint32`.

This commit updates llgo accordingly.

llvm-svn: 288768