Two of them (in the function make_join_statistics and in the function
sort_and_filter_keyuse) were due to bad merges while the third bug was
triggered by uninitialized values of the field JOIN_TAB::preread_init_done.

Fixed a compiler warning in mysql_priv.h.

Commented out some queries from the funcs_1 suite returning wrong
errors due to bugs concerning updatable views (see bugs 784297 and
784303).

Adjusted some results for the test cases with derived tables from
different suites.