Replace some uses of acp with cp

ACP was originally created to overcome differences with cp between
Linux, Darwin, and Windows. We've since dropped Windows as a build host,
and don't use features like '-u' anymore.

For most of our current usecases, 'acp' is identical to 'cp' except that
it splits 'cp -p' into 'acp -p' for mode and ownership, and 'acp -t' for
timestamps. On Linux, this could be specified using
'--preserve=mode,ownership', but Darwin doesn't have this.

Since we're removing the destination file before copying, 'cp' already
preserves the mode (modulated by the umask). So the only extra thing
that gets preserved with 'acp -p' is ownership, which we should not care
about in the build system. (In many cases we shouldn't be preserving
mode either, so that readonly source trees can actually be marked
readonly, but that will be a future change)

Change-Id: Ied96fdc303ac5c774347c07363daec8b6dfb22e4