[38/77] Move SCALAR_INT_MODE_P out of strict_volatile_bitfield_p

[38/77] Move SCALAR_INT_MODE_P out of strict_volatile_bitfield_p

strict_volatile_bitfield_p returns false for any mode that isn't
a scalar integer.  This patch moves the check to the caller and
makes strict_volatile_bitfield_p take the mode as a scalar_int_mode.
The handling of a true return can then also use the mode as a
scalar_int_mode.

2017-08-30  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* expmed.c (strict_volatile_bitfield_p): Change the type of fieldmode
	to scalar_int_mode.  Remove check for SCALAR_INT_MODE_P.
	(store_bit_field): Check is_a <scalar_int_mode> before calling
	strict_volatile_bitfield_p.
	(extract_bit_field): Likewise.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r251490