this patch allows scripts that reside in $fqgitdir/gitweb to be used
for firing up an instaweb server. this lays the groundwork for
extending instaweb support to non-standard web servers, which may
require a script for proper invocation.
Signed-off-by: Mike Dalessio <mike@csa.net> Signed-off-by: Lars Hjemli <hjemli@gmail.com> Signed-off-by: Shawn O. Pearce <spearce@spearce.org>