Using --dailynow --dailychange <hash> makes Regres check out the specified
change to obtain the vk-master.txt from and perform a full run of all the
tests.

Also fix --keep usage.

Bug: none
Change-Id: Ia126bfc136e6b86a6fcc570f79a9293ae97ca392
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/42109Tested-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>