assemble: only be optimistic with NO_SEG if we're really in pass 1
assemble: only be optimistic with NO_SEG if we're really in pass 1

Only be optimistic about the reachability of a symbol with NO_SEG if
we are truly in pass 1, i.e. it could possibly be just a forward
reference.  After we have done a single pass, if it is still NO_SEG,
then it is an absolute symbol and need to be treated as such.

letolabs/nasm,turingstudio/nasm,Distrotech/nasm,turingstudio/nasm,turingstudio/nasm,projedi/nasm,projedi/nasm,techkey/nasm,Distrotech/nasm,Distrotech/nasm,projedi/nasm,turingstudio/nasm,projedi/nasm,projedi/nasm,letolabs/nasm,techkey/nasm,techkey/nasm,techkey/nasm,techkey/nasm,Distrotech/nasm,letolabs/nasm