This contains a copy of libevent-1.4.7-stable, initially 
for use on Linux, but also perhaps on BSD / Solaris / Mac.

Rather than use libevent's own build system, we just build a Chrome 
static library using SConstruct.

Changes from upstream:
1) add config.h from a run of configure on a Linux development box.
2) add SConstruct
3) quotes.patch is applied to allow libevent to be used without
being installed (alternative is adding crazy -I arguments to the commandline)
4) The directories WIN32-Code and WIN32-Prj are not included

SConstruct does not include a few files that don't build on Linux:
    devpoll.c, evport.c, kqueue.c

TODO: currently we -I the source directory, which exposes config.h, which
is dangerous.  We should probably add an include directory of symlinks
back to the real .h files, or something.