[AArch64] Implement new intrinsics vabsd_s64 and vnegd_s64.

[AArch64] Implement new intrinsics vabsd_s64 and vnegd_s64.

gcc/
2018-08-31  Vlad Lazar  <vlad.lazar@arm.com>

	* config/aarch64/arm_neon.h (vabsd_s64): New.
	(vnegd_s64): Likewise.

gcc/testsuite/
2018-08-31  Vlad Lazar  <vlad.lazar@arm.com>

	* gcc.target/aarch64/scalar_intrinsics.c (test_vnegd_s64): New.
	* gcc.target/aarch64/vneg_s.c (RUN_TEST_SCALAR): New.
	(test_vnegd_s64): Likewise.
	* gcc.target/aarch64/vnegd_64.c: New.
	* gcc.target/aarch64/vabsd_64.c: New.
	* gcc.tartget/aarch64/vabs_intrinsic_3.c: New

From-SVN: r264019