[llvm-mc-assemble-fuzzer] Update API - Pass MCObjectWriter instead of a stream

Fixes build breakage of llvm-mc-assemble-fuzzer introduced by r332749.

Fix provided by pbhatu (Pratik Bhatu)



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@339981 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed