DebugInfo: Do not delay attaching DW_AT_inline attribute to abstract definitions.

This is just unneccessary - we only create abstract definitions when
we're inlining anyway, so there's no reason to delay this to see if
we're going to inline anything.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208798 91177308-0d34-0410-b5e6-96231b3b80d8