notmuch-report: Rename from nmbug-status

This script generates reports based on notmuch queries, and doesn't
really have anything to do with nmbug, except for sharing the NMBGIT
environment variable.

diff --git a/devel/nmbug/nmbug-status b/devel/nmbug/notmuch-report
similarity index 100%
rename from devel/nmbug/nmbug-status
rename to devel/nmbug/notmuch-report