sstate.bbclass: Use bb.fatal() instead of raising FuncFailed

This sets a good example and avoids unnecessarily contributing to
perceived complexity and cargo culting.

Motivating quote below:

< kergoth> the *original* intent was for the function/task to error via
           whatever appropriate means, bb.fatal, whatever, and
           funcfailed was what you'd catch if you were calling
           exec_func/exec_task. that is, it's what those functions
           raise, not what metadata functions should be raising
< kergoth> it didn't end up being used that way
< kergoth> but there's really never a reason to raise it yourself

FuncFailed.__init__ takes a 'name' argument rather than a 'msg'
argument, which also shows that the original purpose got lost.

(From OE-Core rev: 33611b69c221cf875eba1c7cb599c256825ae470)

Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/sstate.bbclass

@@ -658,7 +658,7 @@ def sstate_setscene(d):
     shared_state = sstate_state_fromvars(d)
     accelerate = sstate_installpkg(shared_state, d)
     if not accelerate:
-        raise bb.build.FuncFailed("No suitable staging package found")
+        bb.fatal("No suitable staging package found")
 
 python sstate_task_prefunc () {
     shared_state = sstate_state_fromvars(d)