in rev. 1.34. Mainly I missed the fact that the buffer is used for two
purposes:
1) storing a group line from the group file;
2) __gr_parse_entry() parses the buffer and tries to put the group
members to the remaining part of the buffer and can fail if there
is no enough room for them.
Re-arrange the buffer size checks to account the latter case.
Submitted by: Kirk R Webb
MFC after: 2 weeks
0ec15b18a2