real.c (c4x_single_format, [...]): Provide values for signbit_ro for c4x's single...

real.c (c4x_single_format, [...]): Provide values for signbit_ro for c4x's single and extended floating point formats.

	* real.c (c4x_single_format, c4x_extended_format): Provide values
	for signbit_ro for c4x's single and extended floating point formats.
	* optabs.c (expand_copysign): Use the floating point format's
	signbit_ro for expanding via expand_copysign_absneg, and it's
	signbit_rw field for expanding via expand_copysign_bit.

Co-Authored-By: Richard Henderson <rth@redhat.com>
From-SVN: r96530