symlink system Python to hostpython3crystax build dir

Creates an empty hostpython3crystax build directory and symlinks
system python3.5 to it, fixes #1154

Author: AndreMiras

pythonforandroid/recipe.py

@@ -724,6 +724,10 @@ def real_hostpython_location(self):
             return join(
                 Recipe.get_recipe('hostpython2', self.ctx).get_build_dir(),
                 'hostpython')
+        elif 'hostpython3crystax' in self.ctx.recipe_build_order:
+            return join(
+                Recipe.get_recipe('hostpython3crystax', self.ctx).get_build_dir(),
+                'hostpython')
         else:
             python_recipe = self.ctx.python_recipe
             return 'python{}'.format(python_recipe.version)

pythonforandroid/recipes/hostpython3crystax/__init__.py

@@ -1,7 +1,5 @@
-
-from pythonforandroid.toolchain import Recipe, shprint, current_directory, info, warning
-from os.path import join, exists
-from os import chdir
+from pythonforandroid.toolchain import Recipe, shprint
+from os.path import join
 import sh
 
 
@@ -13,14 +11,32 @@ class Hostpython3Recipe(Recipe):
 
     conflicts = ['hostpython2']
 
+    def get_build_container_dir(self, arch=None):
+        choices = self.check_recipe_choices()
+        dir_name = '-'.join([self.name] + choices)
+        return join(self.ctx.build_dir, 'other_builds', dir_name, 'desktop')
+
     # def prebuild_armeabi(self):
     #     # Override hostpython Setup?
     #     shprint(sh.cp, join(self.get_recipe_dir(), 'Setup'),
     #             join(self.get_build_dir('armeabi'), 'Modules', 'Setup'))
 
+    def get_build_dir(self, arch=None):
+        return join(self.get_build_container_dir(), self.name)
+
     def build_arch(self, arch):
+        """
+        Creates expected build and symlinks system Python version.
+        """
         self.ctx.hostpython = '/usr/bin/false'
         self.ctx.hostpgen = '/usr/bin/false'
+        # creates the sub buildir (used by other recipes)
+        # https://github.com/kivy/python-for-android/issues/1154
+        sub_build_dir = join(self.get_build_dir(), 'build')
+        shprint(sh.mkdir, '-p', sub_build_dir)
+        system_python = sh.which("python" + self.version)
+        link_dest = join(self.get_build_dir(), 'hostpython')
+        shprint(sh.ln, '-sf', system_python, link_dest)
 
 
 recipe = Hostpython3Recipe()