[pdb] Get rid of Data and RawData in CVType.

The `CVType` had two redundant fields which were confusing and
error-prone to fill out.  By treating member records as a distinct
type from leaf records, we are able to simplify this quite a bit.

Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D24432

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@281556 91177308-0d34-0410-b5e6-96231b3b80d8
18 files changed