Encode: Fixed a memory leak that occurred in the UTF-8 encoding.

The decode and encode methods allocated a SV for the result, this SV
is passed to the process_utf8() function which may croak() if the
CHECK flag has FB_CROAK set.
bump version number of Encode by _01
add 5.16.3 to Module:Corelist
perldelta: Module::CoreList update
perldelta: Encode update
perlhist: date for 5.16.3-RC1