package/rpi-userland: bump version

Fixes build with glibc-2.22.

Also fixes hard-to-trigger deadlock in highly threaded case, and fix
libraries dependencies.

Misc minor improvements in test programs as well.

Fixes #8446.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: gamadril.dev@gmail.com
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/rpi-userland/rpi-userland.mk

@@ -4,7 +4,7 @@
 #
 ################################################################################
 
-RPI_USERLAND_VERSION = b864a841e5a459a66a890c22b3a34127cd226238
+RPI_USERLAND_VERSION = 8306b7c757f4b8e8d9148789eeb64c666d9244a5
 RPI_USERLAND_SITE = $(call github,raspberrypi,userland,$(RPI_USERLAND_VERSION))
 RPI_USERLAND_LICENSE = BSD-3c
 RPI_USERLAND_LICENSE_FILES = LICENCE