bn/asm/sparcv9-mont.pl: iron another glitch in squaring code path.
This module is used only with odd input lengths, i.e. not used in normal
PKI cases, on contemporary processors. The problem was "illuminated" by
fuzzing tests.
@@ -493,6 +493,9 @@ $code.=<<___;
mulx $npj,$mul1,$acc1
add $tpj,$car1,$car1
ld [$np+$j],$npj ! np[j]
+ srlx $car1,32,$tmp0
+ and $car1,$mask,$car1
+ add $tmp0,$sbit,$sbit
add $acc0,$car1,$car1
ld [$tp+8],$tpj ! tp[j]
add $acc1,$car1,$car1
