Use memmove instead of memcpy on overlapping memory areas.
Use memmove instead of memcpy on overlapping memory areas.

Reported by Bob Alexander <balexander@expressor-software.com> in
<http://thread.gmane.org/gmane.network.ssh.libssh2.devel/2530>.

libssh2/libssh2,libssh2/libssh2,libssh2/libssh2,libssh2/libssh2