bitbake: siggen: Clean up task reference formats

Currently siggen uses the format "<filename>.<taskname>" for referencing tasks
whilst runqueue uses "<filename>:<taskname>". This converts to use ":" as the
separator everywhere.

This is an API breaking change since the cache is affected, as are siginfo files
and any custom signature handlers such as those in OE-Core.

Ultimately this will let us clean up and the accessor functions from runqueue,
removing all the ".rsplit(".", 1)[0]" type code currently all over the place.
Once a standard is used everwhere we can update the code over time to be more
optimal.

(Bitbake rev: 07e539e1c566ca3434901e1a00335cb76c69d496)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/cache.py

@@ -220,7 +220,7 @@ class CoreRecipeInfo(RecipeInfoCommon):
 
         cachedata.hashfn[fn] = self.hashfilename
         for task, taskhash in self.basetaskhashes.items():
-            identifier = '%s.%s' % (fn, task)
+            identifier = '%s:%s' % (fn, task)
             cachedata.basetaskhash[identifier] = taskhash
 
         cachedata.inherits[fn] = self.inherits