kern/misc: Implement faster grub_memcpy() for aligned buffers

When both "dest" and "src" are aligned, copying the data in grub_addr_t
sized chunks is more efficient than a byte-by-byte copy.

Also tweak __aeabi_memcpy(), __aeabi_memcpy4(), and __aeabi_memcpy8(),
since grub_memcpy() is not inline anymore.

Optimization for unaligned buffers was omitted to maintain code
simplicity and readability. The current chunk-copy optimization
for aligned buffers already provides a noticeable performance
improvement (*) for Argon2 keyslot decryption.

  (*) On my system, for a LUKS2 keyslot configured with a 1 GB Argon2
      memory requirement, this patch reduces the decryption time from
      22 seconds to 12 seconds.

Signed-off-by: Gary Lin <glin@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

grub-core/boot/decompressor/minilib.c

@@ -50,6 +50,12 @@ grub_memmove (void *dest, const void *src, grub_size_t n)
   return dest;
 }
 
+void *
+grub_memcpy (void *dest, const void *src, grub_size_t n)
+{
+  return grub_memmove (dest, src, n);
+}
+
 int
 grub_memcmp (const void *s1, const void *s2, grub_size_t n)
 {