uhttpd: fix HTTP incompatibilities in file handler

 * Fixes sending an extraneous message body for 204 and 304 resoponses which
   breaks Chrome in keep-alive mode.

 * Adds mimetypes for JSON and JSONP.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43078 3c298f89-4303-0410-b956-a3cf2f4a3e73
mac80211: fix key flush handling in AP+STA

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43079 3c298f89-4303-0410-b956-a3cf2f4a3e73
px5g-standalone: use /dev/urandom to initialize serial (#18232)

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43080 3c298f89-4303-0410-b956-a3cf2f4a3e73