Associate the version-when-defined with definitions of standard DWARF
constants. Identify the "vendor" for DWARF extensions.
Use this information to verify FORMs in .debug_abbrev are defined as
of the DWARF version specified in the associated unit.
Removed two tests that had specified DWARF v1 (which essentially does
not exist).
Differential Revision: http://reviews.llvm.org/D30785
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300875 91177308-0d34-0410-b5e6-96231b3b80d8