1. it's wrong to use memcpy() for overlapped areas;
  2. we use it only once.
During merge to 4.1 will remove a memcpy_overlap() call 
from strings/ctype-tis620.c as well in order to fix 
bug #10836: ctype_tis620 test failure with ICC-compiled binaries on IA64.


myisam/mi_search.c:
  use memmove() instead, as memcpy_overlap() is removed.