memcpy seems to always require dest as return value.

fixes test_hwcomposer on mako with hybris_13 adaptation

NAME
       memcpy - copy memory area

SYNOPSIS
       #include <string.h>

       void *memcpy(void *dest, const void *src, size_t n);

DESCRIPTION
       The memcpy() function copies n bytes from memory area src to
memory area dest.  The memory areas must not overlap.  Use memmove(3) if
the memory areas do overlap.

RETURN VALUE
       The memcpy() function returns a pointer to dest.

hybris/common/hooks.c

@@ -285,7 +285,7 @@ static void *_hybris_hook_memcpy(void *dst, const void *src, size_t len)
     TRACE_HOOK("dst %p src %p len %zu", dst, src, len);
 
     if (src == NULL || dst == NULL)
-        return NULL;
+        return dst;
 
     return memcpy(dst, src, len);
 }