[DWARF parser] Make a few methods non-public

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207156 91177308-0d34-0410-b5e6-96231b3b80d8
Function defined in a header should be inline. Found by modules build.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207157 91177308-0d34-0410-b5e6-96231b3b80d8
Add missing include, found by modules build.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207158 91177308-0d34-0410-b5e6-96231b3b80d8