Stop creating MCSectionData is the ELF writer.

Now is is just its use of MCSymbolData that requires it to take a non const
MCAssembler.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237951 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed