gfsplit: don't produce share number 0 (Debian bug#556939)
gfsplit: don't produce share number 0 (Debian bug#556939)

Mathematically, share number 0 would be a verbatim copy of the secret,
which we obviously don't want.
      
In fact, due to implementation details of libgfshare, we produce a
duplicate copy of share number 1, which fails to recombine correctly.

djpohly/libgfshare,periodic1236/libgfshare,jcushman/libgfshare,periodic1236/libgfshare,djpohly/libgfshare,jcushman/libgfshare