lib/memcopy: use glibc version

the kernel's memcpy and memmove is very inefficient. But the glibc version is
quite fast, in some cases it is 10 times faster than the kernel version. So I
introduce some memory copy macros and functions of the glibc to improve the
kernel version's performance.

The strategy of the memory functions is:
1. Copy bytes until the destination pointer is aligned.
2. Copy words in unrolled loops.  If the source and destination are not
   aligned in the same way, use word memory operations, but shift and merge
   two read words before writing.
3. Copy the few remaining bytes.

Change-Id: I386f4b021f6d38d8bc102d27a0a5fa403dcb78c8
Signed-off-by: Miao Xie <miaox*******>
Signed-off-by: faux123 <reioux@gmail.com>
Merge "lib/memcopy: use glibc version" into android-4.4