Now that branches are in a separate C namespace, we can remove
the restrictions in the parser that claim a branch name would
collide with QMP, and delete the negative tests that are no
longer problematic.  A separate patch can then add positive
tests to qapi-schema-test to test that any corner cases will
compile correctly.

This reverts the scripts/qapi.py portion of commit 7b2a5c2f,
now that the assertions that it plugged are no longer possible.
Signed-off-by: NEric Blake <eblake@redhat.com>
Message-Id: <1447836791-369-15-git-send-email-eblake@redhat.com>
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>