bitbake: Implement signatures

Includes functionality to find out what changes between two different singature data dumps.

Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

bitbake/lib/bb/parse/__init__.py

@@ -28,6 +28,7 @@ handlers = []
 
 import bb, os
 import bb.utils
+import bb.siggen
 
 class ParseError(Exception):
     """Exception raised when parsing fails"""
@@ -79,6 +80,9 @@ def init(fn, data):
         if h['supports'](fn):
             return h['init'](data)
 
+def init_parser(d):
+    bb.parse.siggen = bb.siggen.init(d)
+
 def resolve_file(fn, d):
     if not os.path.isabs(fn):
         bbpath = bb.data.getVar("BBPATH", d, True)