arm: Fix polymorphic variants failing with undefined reference to `__ARM_undef` error.

arm: Fix polymorphic variants failing with undefined reference to `__ARM_undef` error.

This patch fixes the issue mentioned in PR101016, which is mve polymorphic variants
failing at linking with undefined reference to "__ARM_undef" error.

gcc/ChangeLog:

2021-06-11  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

	PR target/101016
	* config/arm/arm_mve.h (__arm_vld1q): Change __ARM_mve_coerce(p0,
	int8_t const *) to __ARM_mve_coerce1(p0, int8_t *) in the argument for
	the polymorphic variants matching code.
	(__arm_vld1q_z): Likewise.
	(__arm_vld2q): Likewise.
	(__arm_vld4q): Likewise.
	(__arm_vldrbq_gather_offset): Likewise.
	(__arm_vldrbq_gather_offset_z): Likewise.

gcc/testsuite/ChangeLog:

2021-06-11  Srinath Parvathaneni  <srinath.parvathaneni@arm.com>

	PR target/101016
	* gcc.target/arm/mve/intrinsics/pr101016.c: New test.

(cherry picked from commit b13f297f01c943aa167f7c6eb94bed40dce0d553)