Fix a stack overflow in the assembler when checking that GEPs must be over sized...

Fix a stack overflow in the assembler when checking that GEPs must be over sized types.

We failed to use a marking set to properly handle recursive types, which caused use
to recurse infinitely and eventually overflow the stack.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231760 91177308-0d34-0410-b5e6-96231b3b80d8