Add Python for cross-platform builds

Signed-off-by: Patrick Avery <[email protected]>

Author: psavery

conda.recipe/meta.yaml

@@ -11,6 +11,9 @@ build:
     - hexrdgui = hexrdgui.main:main
 
 requirements:
+  build:
+    - python {{ python }}                    # [build_platform != target_platform]
+    - cross-python_{{ target_platform }}     # [build_platform != target_platform]
   host:
     - python {{ python }}
     - setuptools