bc,dc: make BC_LINE_LENGTH/DC_LINE_LENGTH more compatible with GNU

function                                             old     new   delta
xc_vm_init                                           640     682     +42

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/testsuite/dc_subtract_results.txt b/testsuite/dc_subtract_results.txt
index 9f77262..0a97623 100644
--- a/testsuite/dc_subtract_results.txt
+++ b/testsuite/dc_subtract_results.txt
@@ -8,15 +8,15 @@
 2874519803456326214611
 9000000000000000000000000000000000000001
 1
-9000000000000000000000000000000000000000.000000000000000000000000000\
-00000001
+9000000000000000000000000000000000000000.0000000000000000000000000000\
+0000001
 .0000000000000000000000000000000001
-9999999999999999999999999999999999999999.999999999999999999999999999\
+9999999999999999999999999999999999999999.9999999999999999999999999999\
+9999999999999999999999999999999999999999999999999999999999
+10000000000000000000000000000000000000000.999999999999999999999999999\
 99999999999999999999999999999999999999999999999999999999999
-10000000000000000000000000000000000000000.99999999999999999999999999\
-999999999999999999999999999999999999999999999999999999999999
-10000000000000000000000000000000000000000.00000000009999999999999999\
-99999999999999999999999999999999999999999999999999
+10000000000000000000000000000000000000000.000000000099999999999999999\
+9999999999999999999999999999999999999999999999999
 -8
 -182934721309467230894628759280719690
 1245723576605103923392087218483