Fix target/101934: aarch64 memset code creates unaligned stores for -mstrict-align

Fix target/101934: aarch64 memset code creates unaligned stores for -mstrict-align

The problem here is the aarch64_expand_setmem code did not check
STRICT_ALIGNMENT if it is creating an overlapping store.
This patch adds that check and the testcase works.

gcc/ChangeLog:

	PR target/101934
	* config/aarch64/aarch64.c (aarch64_expand_setmem):
	Check STRICT_ALIGNMENT before creating an overlapping
	store.

gcc/testsuite/ChangeLog:

	PR target/101934
	* gcc.target/aarch64/memset-strict-align-1.c: New test.