Update tests to use the new format of printing a TimeValue. It's a bit

Update tests to use the new format of printing a TimeValue. It's a bit
odd to have the output of 'llvm-ar tv' depend on the format of
TimeValue::str(), but that's what we have today. If anyone needs the
output to remain compatible with GNU ar or old versions of llvm-ar, just
shout and I'll switch the code to manually format its times.

Note that there isn't a portable format -- Mac and GNU have different
formats at least (thanks Rafael!) so...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207387 91177308-0d34-0410-b5e6-96231b3b80d8