[package] uhttpd: do not subscribe to epoll write events

[package] uhttpd: do not subscribe to epoll write events
Watch child read pipe end for data instead of relying on socket write
notification to process cgi data, should lower cpu consumption during
requests on weaker devices.

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@32640 3c298f89-4303-0410-b956-a3cf2f4a3e73