The problem is that a unfiltered user query was being passed as
the format string parameter of sql_print_warning which later
performs printf-like formatting, leading to crashes if the user
query contains formatting instructions (ie: %s). Also, it was
using THD::query as the source of the user query, but this
variable is not meaningful in some situations -- in a delayed
insert, it points to the table name.

The solution is to pass the user query as a parameter for the
format string and use the function parameter query_arg as the
source of the user query.

mysql-test/suite/binlog/r/binlog_unsafe.result:
  Add test case result for Bug#42634
mysql-test/suite/binlog/t/binlog_unsafe.test:
  Add test case for Bug#42634
sql/sql_class.cc:
  Don't pass the user query as a format string.