initialization crashes server.
  Make sure variables are initialized to something (like null) when
  the default initialization fails and a continue handler is in effect.


mysql-test/r/sp.result:
  New test case for BUG#14643.
mysql-test/t/sp.test:
  New test case for BUG#14643.
sql/sp_head.cc:
  Make sure variables are initialized to something (like null) when
  the default initialization fails and a continue handler is in effect.
  If this also fails (out of memory), we have to abort without letting
  the handler catch.