Two parse.c operand defects. A bare `-8` (no $) double-negated to
+8: a_parsenum lets strtoll consume the sign, and the caller's
`off * sign` re-applied it (the D_INDIR arm never multiplied, which
is why -8(BP) always worked); the wwstage twin was already correct,
so this was a latent cs!=ww on hand-written source. The name(REG)
non-SB arm faked a D_INDIR off an UNCHECKED reg_lookup and silently
discarded the parsed ident and +disp -- both stages; the shape has
no encoding and now rejects loud.