tbl command segfault

[mtbakerguy]

If you have a table with 37 columns, you will consistently crash tbl as the reg function will overrun the nregs array and SEGFAULT:

.sp 1 .ce 1 .ps +10 Deployments .sp 1 .ps -10 .ce 0 .TS center, box, tab(;); cB s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s l | c1 | c1 | c1 | c1| c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1 | c1. Area _ .TE

While handling an arbitrary number of columns would be nice, it shouldn't crash at a minimum.

[mtbakerguy]

Relevant aside: the demo Makefile hides crashes as it'll go ahead and happily generate an empty PDF even though a crash happened much earlier in the pipeline.