Re: [tz] zic throws warning for 2007a

Thanks for reporting the problem. For now let's work around it by changing the abbreviation to "MMT"; although "MMT" is not technically correct, I expect it's better than overrunning the POSIX limit. This prompted me to go back to old sources (wow, printed books!) to nail down Liberia's pre-1972 UT offset and the date of its 1972 transition to GMT. Proposed patch attached. It would be interesting to know where Liberia's -0:44:30 came from. There's not much of interest on that longitude line (equivalent to 11 degrees 7 minutes 30 seconds west).