bc: do not pass line width in parameters, it's in globals

bc: do not pass line width in parameters, it's in globals

function                                             old     new   delta
bc_num_printNewline                                   36      47     +11
bc_num_printHex                                       70      62      -8
bc_num_printDigits                                   142     132     -10
bc_program_printStream                               185     173     -12
bc_program_print                                     773     754     -19
bc_num_printNum                                      563     538     -25
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/5 up/down: 11/-74)            Total: -63 bytes
   text	   data	    bss	    dec	    hex	filename
 985122	    485	   7296	 992903	  f2687	busybox_old
 985059	    485	   7296	 992840	  f2648	busybox_unstripped

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