Move generated gitweb_config.perl to hidden tmp directory

Since some systems have a /tmp autocleaner, we don't want to trust
our gitweb configuration file to stay there.  Instead keep it with
the extracted WARs inside of our own private temporary location.

Change-Id: I5f4dea46a755bf3296f15ae38361452fe8df6655
Signed-off-by: Shawn O. Pearce <sop@google.com>
3 files changed