bc: "unsigned_n > 0" is shorter code than "unsigned_n >= 1"

bc: "unsigned_n > 0" is shorter code than "unsigned_n >= 1"

function                                             old     new   delta
zbc_program_print                                    680     677      -3
zbc_program_exec                                    4089    4085      -4
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-7)               Total: -7 bytes
   text	   data	    bss	    dec	    hex	filename
 981404	    485	   7296	 989185	  f1801	busybox_old
 981397	    485	   7296	 989178	  f17fa	busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>