Revert "Exclude 'from typing import *' from linter."

This reverts commit d936bf61f9.

We no longer need this since we've migrated to specifying the
dependencies in the typing module that we're actually using.

tools/lint-all

@@ -71,7 +71,6 @@ def check_pyflakes():
             if options.full or not \
                     ('imported but unused' in ln or
                      'redefinition of unused' in ln or
-                     "'from typing import *' used; unable to detect undefined names" in ln or
                      ("zerver/models.py" in ln and
                       " undefined name 'bugdown'" in ln) or
                      ("scripts/lib/pythonrc.py" in ln and