af-binder: Fix hangup on long messages

af-binder: Fix hangup on long messages

Fixes:

 - Handle correctly the sending of very long
messages.

Improvements:

 - Better handling of sd_event loop

 - Allows settings of afb-daemon options by
   environment:
     AFB_TRACEREQ, AFB_TRACEDITF, AFB_TRACESVC,
     AFB_TRACEEVT, AFB_LDPATHS

Bug-AGL: SPEC-1091

Change-Id: I1bf8d52bf3ab8f1c73a524c0030b388570d08da8
Signed-off-by: José Bollo <jose.bollo@iot.bzh>
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/12193
Reviewed-by: José Bollo <jobol@nonadev.net>
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-build: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>