[AArch64][SVE] Add ABS support

[AArch64][SVE] Add ABS support

For some reason we missed ABS out of the list of supported integer
operations when adding the SVE port initially.

2018-12-20  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* config/aarch64/iterators.md (SVE_INT_UNARY, fp_int_op): Add abs.
	(SVE_FP_UNARY): Sort.

gcc/testsuite/
	* gcc.target/aarch64/pr64946.c: Force nosve.
	* gcc.target/aarch64/ssadv16qi.c: Likewise.
	* gcc.target/aarch64/usadv16qi.c: Likewise.
	* gcc.target/aarch64/vect-abs-compile.c: Likewise.
	* gcc.target/aarch64/sve/abs_1.c: New test.

From-SVN: r267304