arm: [MVE intrinsics] Fix support for loads [PR target/114323]

arm: [MVE intrinsics] Fix support for loads [PR target/114323]

The testcase in this PR shows that we would load from an uninitialized
location, because the vld1 instrinsics are reported as "const". This
is because function_instance::reads_global_state_p() does not take
CP_READ_MEMORY into account.  Fixing this gives vld1 the "pure"
attribute instead, and solves the problem.

2024-03-15  Christophe Lyon  <christophe.lyon@linaro.org>

	PR target/114323
	gcc/
	* config/arm/arm-mve-builtins.cc
	(function_instance::reads_global_state_p): Take CP_READ_MEMORY
	into account.

	gcc/testsuite/
	* gcc.target/arm/mve/pr114323.c: New.