The DebugDirectory contains a pointer to the CodeView info structure which is a
derivative of the OMF debug directory. The structure has evolved a bit over
time, and PDB 2.0 used a slightly different definition from PDB 7.0. Both of
these are specific to CodeView and not COFF. Reflect this by moving the
structure definitions into the DebugInfo/CodeView headers. Define a generic
DebugInfo union type that can be used to pass around a reference to the
DebugInfo irrespective of the versioning. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278075 91177308-0d34-0410-b5e6-96231b3b80d8
