Fixed error introduced in MySQLProtocolParser

When originally moved the fix out of the pt-query-digest into
MySQLProtocolParser I made a mistake and I've introduced an error.
Fixed.

lib/MySQLProtocolParser.pm

@@ -1223,7 +1223,7 @@ sub parse_client_handshake_packet {
    my ( $db ) = $data =~ m!
       ^.{64}${user}00..   # Everything matched before
       (?:..){$code_len}   # The scramble buffer
-      (.*)00.*\Z          # The database name
+      (.*?)00.*\Z         # The database name
    !x;
    my $pkt = {
       user  => to_string($user),