Inline doc, code formatting, and micro-optimizations to `BP_Groups_Group::populate()`.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7976 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
POT, generated from r7976

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7977 cdf35c40-ae34-48e0-9cc9-0c9da1808c22