WL#3432 (Compile the Parser with a --debug --verbose option)

Changed the automake build process :
- ./configure.in
- ./sql/Makefile.am
to compile an instrumented parser for debug=yes or debug=full builds

Changed the (primary) runtime invocation of the parser :
- sql/sql_parse.cc
to generate bison traces in stderr when the DBUG "parser_debug" flag is set.

sql/sql_parse.cc

@@ -5776,6 +5776,26 @@ void mysql_init_multi_delete(LEX *lex)
   lex->query_tables_last= &lex->query_tables;
 }
 
+#ifndef DBUG_OFF
+static void turn_parser_debug_on()
+{
+  /*
+     MYSQLdebug is in sql/sql_yacc.cc, in bison generated code.
+     Turning this option on is **VERY** verbose, and should be
+     used when investigating a syntax error problem only.
+
+     The syntax to run with bison traces is as follows :
+     - Starting a server manually :
+       mysqld --debug="d,parser_debug" ...
+     - Running a test :
+       mysql-test-run.pl --mysqld="--debug=d,parser_debug" ...
+
+     The result will be in the process stderr (var/log/master.err)
+   */
+  extern int MYSQLdebug;
+  MYSQLdebug= 1;
+}
+#endif
 
 /*
   When you modify mysql_parse(), you may need to mofify
@@ -5785,6 +5805,9 @@ void mysql_init_multi_delete(LEX *lex)
 void mysql_parse(THD *thd, char *inBuf, uint length)
 {
   DBUG_ENTER("mysql_parse");
+
+  DBUG_EXECUTE_IF("parser_debug", turn_parser_debug_on(););
+
   mysql_init_query(thd, (uchar*) inBuf, length);
   if (query_cache_send_result_to_client(thd, inBuf, length) <= 0)
   {