[dsymutil] Check archive members timestamps.

[dsymutil] Check archive members timestamps.

The debug map contains the timestamp of the object files in references.
We do not check these in the general case, but it's really useful if
you have archives where different versions of an object file have been
appended. This allows llvm-dsymutil to find the right one.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242965 91177308-0d34-0410-b5e6-96231b3b80d8