android build: pin hashes of p4a recipes

contrib/android/p4a_recipes/libffi/__init__.py

@@ -0,0 +1,18 @@
+import os
+
+from pythonforandroid.recipes.libffi import LibffiRecipe
+from pythonforandroid.util import load_source
+
+util = load_source('util', os.path.join(os.path.dirname(os.path.dirname(__file__)), 'util.py'))
+
+
+assert LibffiRecipe._version == "v3.3"
+assert LibffiRecipe.depends == []
+assert LibffiRecipe.python_depends == []
+
+
+class LibffiRecipePinned(util.InheritedRecipeMixin, LibffiRecipe):
+    sha512sum = "62798fb31ba65fa2a0e1f71dd3daca30edcf745dc562c6f8e7126e54db92572cc63f5aa36d927dd08375bb6f38a2380ebe6c5735f35990681878fc78fc9dbc83"
+
+
+recipe = LibffiRecipePinned()