Fix issue 5280, build table without coldefs.
Fix issue 5280, build table without coldefs.

mhvk/astropy,mhvk/astropy,larrybradley/astropy,lpsinger/astropy,saimn/astropy,lpsinger/astropy,astropy/astropy,pllim/astropy,StuartLittlefair/astropy,pllim/astropy,pllim/astropy,larrybradley/astropy,larrybradley/astropy,StuartLittlefair/astropy,larrybradley/astropy,pllim/astropy,astropy/astropy,lpsinger/astropy,mhvk/astropy,StuartLittlefair/astropy,mhvk/astropy,lpsinger/astropy,lpsinger/astropy,pllim/astropy,astropy/astropy,StuartLittlefair/astropy,saimn/astropy,saimn/astropy,astropy/astropy,saimn/astropy,astropy/astropy,saimn/astropy,mhvk/astropy,larrybradley/astropy,StuartLittlefair/astropy