[Debug Info] replace DIUnspecifiedParameter with DITrivialType.
This is the first of a series of patches to handle type uniqueing of the
type array for a subroutine type.
This commit makes sure unspecified_parameter is a DIType to enable converting
the type array for a subroutine type to an array of DITypes.
This commit should have no functionality change. With this commit, we may
change unspecified type to be a DITrivialType instead of a DIType.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214111
91177308-0d34-0410-b5e6-
96231b3b80d8