Fix combined function index abbrev (NFC)

Fix combined function index abbrev (NFC)

Removed an unused abbrev op in the VST_CODE_COMBINED_FNENTRY abbrev.

I noticed while writing/testing an array string dumper for
llvm-bcanalyze that the combined function's VST entry abbrevs contained
an old field that I am not using. Everything was working fine since the
bitcode writer and reader were in sync on how the record fields were
actually being set up and interpreted.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249691 91177308-0d34-0410-b5e6-96231b3b80d8