[AArch64] Add SVE support for integer division

[AArch64] Add SVE support for integer division

After the previous patch to prevent pessimisation of divisions
by constants, this patch adds support for the SVE integer division
instructions.

2018-05-25  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* config/aarch64/iterators.md (SVE_INT_BINARY_SD): New code iterator.
	(optab, sve_int_op): Handle div and udiv.
	* config/aarch64/aarch64-sve.md (<optab><mode>3): New expander
	for SVE_INT_BINARY_SD.
	(*<optab><mode>3): New insn for the same.

gcc/testsuite/
	* gcc.target/aarch64/sve/div_1.c: New test.
	* gcc.target/aarch64/sve/div_1_run.c: Likewise.
	* gcc.target/aarch64/sve/mul_highpart_2.c: Likewise.
	* gcc.target/aarch64/sve/mul_highpart_2_run.c: Likewise.

From-SVN: r260712