bdlt_datetime: Remove trailing enum comma.
bdlt_datetime: Remove trailing enum comma.

The trailing comma causes a compiler warning when using Oracle CC.

frutiger/bde,che2/bde,dbremner/bde,saxena84/bde,osubboo/bde,osubboo/bde,RMGiroux/bde-allocator-benchmarks,che2/bde,jmptrader/bde,RMGiroux/bde-allocator-benchmarks,minhlongdo/bde,osubboo/bde,bloomberg/bde-allocator-benchmarks,apaprocki/bde,dbremner/bde,saxena84/bde,bowlofstew/bde,bowlofstew/bde,RMGiroux/bde-allocator-benchmarks,dharesign/bde,dbremner/bde,jmptrader/bde,frutiger/bde,minhlongdo/bde,bowlofstew/bde,jmptrader/bde,idispatch/bde,dharesign/bde,apaprocki/bde,bloomberg/bde-allocator-benchmarks,gbleaney/Allocator-Benchmarks,bloomberg/bde,idispatch/bde,saxena84/bde,apaprocki/bde,mversche/bde,mversche/bde,bloomberg/bde,minhlongdo/bde,dharesign/bde,bloomberg/bde,RMGiroux/bde-allocator-benchmarks,jmptrader/bde,bloomberg/bde,frutiger/bde,gbleaney/Allocator-Benchmarks,frutiger/bde,gbleaney/Allocator-Benchmarks,che2/bde,apaprocki/bde,dharesign/bde,apaprocki/bde,mversche/bde,osubboo/bde,RMGiroux/bde-allocator-benchmarks,bloomberg/bde-allocator-benchmarks,idispatch/bde,idispatch/bde,mversche/bde,che2/bde,bloomberg/bde,minhlongdo/bde,dbremner/bde,bloomberg/bde-allocator-benchmarks,saxena84/bde,gbleaney/Allocator-Benchmarks,bloomberg/bde-allocator-benchmarks,bowlofstew/bde