getlines: last line of file should always have a newline

This is a useful behavior if you want to reorder the lines,
because otherwise you might end up with originally two lines
on one, e.g.

	$ echo -ne "foo\nbar" | sort
	barfoo

libutil/getlines.c

@@ -24,4 +24,9 @@ getlines(FILE *fp, struct linebuf *b)
 		memcpy(b->lines[b->nlines-1], line, linelen);
 	}
 	free(line);
+	if (strchr(b->lines[b->nlines-1], '\n') == NULL) {
+		b->lines[b->nlines-1] = erealloc(b->lines[b->nlines-1], linelen + 1);
+		b->lines[b->nlines-1][linelen-1] = '\n';
+		b->lines[b->nlines-1][linelen] = '\0';
+	}
 }