Changes

Z: Short circuit memCmp methods if addresses are equal

If addresses of two blocks of memory are equal, the content is equal too.
We can jump to the end label without comparing the content.
Four methods are updated to handle signed and unsigned result as well as constant and variable length.

Signed-off-by: Ehsan Kiani Far <ehsan.kianifar@gmail.com>
 (commit: 4af016d)