gcc-sanitizers.inc: Workaround for aarch64

gcc-sanitizers.inc: Workaround for aarch64

When using the -fsanitize=address  CXX_FLAG for a program compiled for
aarch64 / arm64

This is happing:
MemorySanitizer: CHECK failed: sanitizer_allocator_primary64.h:133 "((kSpaceBeg))
 == ((address_range.Init(TotalSpaceSize, PrimaryAllocatorName, kSpaceBeg)))"
 (0xe00000000000, 0xfffffffffffffff4) (tid=51745)

With -DSANITIZER_CAN_USE_ALLOCATOR64=0 this is not happening and
potenial bugs are detected.

ARM32 does not require this patch.

More info about the issue in this thread:
https://github.com/llvm/llvm-project/issues/65144

Signed-off-by: Thomas Roos <throos@amazon.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Ross Burton <ross.burton@arm.com>