softfloat: return low bits of quotient from floatx80_modrem

softfloat: return low bits of quotient from floatx80_modrem

Both x87 and m68k need the low parts of the quotient for their
remainder operations.  Arrange for floatx80_modrem to track those bits
and return them via a pointer.

The architectures using float32_rem and float64_rem do not appear to
need this information, so the *_rem interface is left unchanged and
the information returned only from floatx80_modrem.  The logic used to
determine the low 7 bits of the quotient for m68k
(target/m68k/fpu_helper.c:make_quotient) appears completely bogus (it
looks at the result of converting the remainder to integer, the
quotient having been discarded by that point); this patch does not
change that, but the m68k maintainers may wish to do so.

Signed-off-by: Joseph Myers <[email protected]>
Reviewed-by: Richard Henderson <[email protected]>
Message-Id: <alpine.DEB.2.21.2006081656500[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>