[44/77] Make simplify_and_const_int take a scalar_int_mode

[44/77] Make simplify_and_const_int take a scalar_int_mode

After previous patches, top-level calls to simplify_and_const_int
always pass a scalar_int_mode.  The only call site that needs to
be updated is the recursive one in simplify_and_const_int_1,
at which point we know "varop" has a scalar integer mode.

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

gcc/
	* combine.c (simplify_and_const_int): Change the type of the mode
	parameter to scalar_int_mode.
	(simplify_and_const_int_1): Likewise.  Update recursive call.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r251496