package/avahi: bump to version 0.8

package/avahi: bump to version 0.8

This bump also includes:
 * Drop upstream security patch which is included in the new version
 * Unconditionally disable support for Qt5 [1] (same as Qt3 and Qt4)
 * Drop dependency on host-inttool, as avahi switched to host-gettext [2]
 * Conditionally enable support for libevent [3]

[1] https://github.com/lathiat/avahi/commit/5dbb32767ae3f5a371cfbd04b4e3a9a634b8efc4
[2] https://github.com/lathiat/avahi/commit/3d5a0c68057e2ed76187a0bb565baaa10d566003
[3] https://github.com/lathiat/avahi/commit/998e20cd76927ce978fb5676820a38308e21f45d

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>