recipetool: create: add additional extension mechanisms

Add a means of extending the dependency extraction for autotools and
cmake.

Note: in order to have this work, you need to have an __init__.py in the
lib/recipetool directory within your layer along with the module
implementing the handlers, and the __init__.py needs to contain:

  # Enable other layers to have modules in the same named directory
  from pkgutil import extend_path
  __path__ = extend_path(__path__, __name__)

(From OE-Core rev: 915dea9f89cd737e5ba167c384e8d314c5c23c49)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/recipetool/create_buildsys_python.py

@@ -716,4 +716,4 @@ def has_non_literals(value):
 
 def register_recipe_handlers(handlers):
     # We need to make sure this is ahead of the makefile fallback handler
-    handlers.insert(0, PythonRecipeHandler())
+    handlers.append((PythonRecipeHandler(), 70))