patch: don't reject final hunk in context diff

* If EOF is seen, process all hunks seen and terminate
* I was debugging why a "short hunk ignored" error occurred for the last hunk in a 2-hunk diff
* undef was being matched against valid-diff-line regex, but undef means there are no more lines in the diff to process

Author: mknos

bin/patch

@@ -185,6 +185,7 @@ while (<PATCH>) {
             print PATCH;
             for ($o_start..$o_end) {
                 $_ = <PATCH>;
+                last unless defined $_; # EOF: no further hunks
                 unless (s/$re/$1/) {
                     $patch->note("Short hunk ignored.\n");
                     $patch->reject($i_range, @i_hunk, $o_range, @o_hunk);