libmysql/libmysql.c:
  Fixes a very rare bug when variable name (without '_') and it's 
  value are at the very end of the config file.
  
  I have tested it , but would liek little mobster to test it further
mysql-test/r/union.result:
  results for union test that proves that EXPLAIN UNION bugs are fixed
mysql-test/t/union.test:
  additional tests for EXPLAIN on UNION's that have previously failed
sql/sql_yacc.yy:
  Some small fixes for newer parsers.
  Only unsigned int yystacksize remains to be fixed.
  This I leave to Monty.
  Present fixes are only aesthetic and do not harm.