IR: Annotate dump methods with LLVM_DUMP_METHOD

It turns out we have a macro to ensure that debuggers can access
`dump()` methods.  Use it.  Hopefully this will prevent me (and others)
from committing crimes like in r223802 (search for /10000/, or just see
the fix in r224407).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230555 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed