Fixes to `vvi` related to pushing the most negative number to the stack.

[vvhitespace] / tests / 6001_push_intmin.pvvs

@ This tests the interpreters ability to push the
@ most negative number directly to the stack.

@ Construct the number -(2^63) on the stack indirectly.
SSTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTN  | -((2^63)-1)
SSSTN                                                                | PUSH 1
TSST                                                                 | SUBTRACT

@ Now push -(2^63) directly onto the stack.
SSTTSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSN | -(2^63)

@ See if the interpreter thinks -((2^63)-1) - 1 == -(2^63)
@ Print 1 for true and 0 for false.
TSST   | SUBTRACT
NTSTN  | BRZ > 1
SSSSN  | PUSH 0
TNST   | PUTDIGIT
NNN    | DIE
NSSVTN | Mark: 1
SSSTN  | PUSH 1
TNST   | PUTDIGIT
NNN    | DIE