#2 [PATCH] ri-li fails to build on gcc-11 due to pointer order comparison

[Sergei Trofimovich]

ri-li fails to build on gcc-11 due to pointer order comparison:

tableau.cc:90:9: error: ordered comparison of pointer with integer zero ('unsigned char*' and 'int')
   90 |   if(Buf<=0) return false;
      |      ~~~^~~

Attaching the trivial fix.