httpd: allow '-h' to work when daemonized with NOMMU enabled

httpd: allow '-h' to work when daemonized with NOMMU enabled

Commit d1b75e184 (httpd: permit non-default home directory with NOMMU
enabled) only works when used with the '-f' (foreground) option.

When '-f' isn't specified and NOMMU is enabled bb_daemonize_or_rexec()
is called to daemonize the server.  Since the server process has been
re-execed the previous patch results in the xchdir() not being called.

Fix this by resetting the re_execed variable in this case.

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>