Turn MCSectionData into a field of MCSection.

This also changes MCAssembler to store a vector of MCSections instead of an
iplist of MCSectionData.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@238159 91177308-0d34-0410-b5e6-96231b3b80d8
8 files changed