include mypyc/ir/*.py in the sdist

Author: mr-c

MANIFEST.in

@@ -5,6 +5,7 @@ recursive-include docs *
 recursive-include mypy/typeshed *.py *.pyi
 recursive-include mypy/xml *.xsd *.xslt *.css
 recursive-include mypyc/lib-rt *.c *.h *.tmpl
+recursive-include mypyc/ir *.py
 include mypy_bootstrap.ini
 include mypy_self_check.ini
 include LICENSE