Patching: added a standard strlcpy() function

[jpaulin]

This is a vanilla implementation of the (apparently missing) strlcpy function.

It is a safer version of ordinary clib strcpy - which does not have a length restriction in place.

strlcpy is always called with a maximum length of the string to be copied. Thus the algorithm terminates when either a null (0) byte is found in source, or when the length is reached.