dc: make "dc -1.23 ..." work

function                                             old     new   delta
stack_machine                                         97     103      +6
dc_main                                              121     110     -11
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(add/remove: 0/0 grow/shrink: 2/2 up/down: 9/-58)             Total: -49 bytes

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