- Address review feedback R4: better comments, formatting

- Addressing review feedback, generation 4.

include/my_global.h:
  Make ALIGN_PTR's action correspond to that of ALIGN_SIZE
sql/item.cc:
  MWL#17: Table-elimination
  - Review feedback: function renames, better comments
sql/item.h:
  MWL#17: Table-elimination
  - Review feedback: function renames, better comments
sql/item_cmpfunc.cc:
  MWL#17: Table-elimination
  - Review feedback: function renames, better comments
sql/item_subselect.cc:
  MWL#17: Table-elimination
  - Review feedback: function renames, better comments
sql/item_subselect.h:
  MWL#17: Table-elimination
  - Review feedback: function renames, better comments
sql/opt_table_elimination.cc:
  MWL#17: Table-elimination
  - Addressing review feedback, generation 4: abstract everything in case
    we would need to change it for something else in the future.
sql/sql_list.h:
  MWL#17: Table-elimination
  - Introduce exchange_sort(List<T> ...) template function
sql/sql_select.cc:
  MWL#17: Table-elimination
  - Review feedback: function renames, better comments

- Fix a trivial problem when OR-merging two multi-equalities
- Amend testsuite to provide full gcov coverage

mysql-test/r/table_elim.result:
  MWL#17: Table elimination:
  - Amend testsuite to provide full gcov coverage
mysql-test/t/table_elim.test:
  MWL#17: Table elimination:
  - Amend testsuite to provide full gcov coverage

- add process-gcov-annotations.pl script that processes .gcov files 
  according to purecov annotations in source code
- add --gcov-src-dir=subdir option to mysql-test-run so that one can
  do gcov processing only for source files in a certain directory.

- Mark gcov deadcode

- More test coverage
- Remove unused code

- Add more testcases.
- Fix trivial compile failure
- Remove handling of "column IN (one_element)". This is converted to equality 
  elsewhere

mysql-test/r/table_elim.result:
  MWL#17: Table elimination
  - Add more testcases.
  - Fix trivial compile failure
mysql-test/t/table_elim.test:
  MWL#17: Table elimination
  - Add more testcases
sql/mysqld.cc:
  MWL#17: Table elimination
  - Fix trivial compile failure
sql/opt_table_elimination.cc:
  MWL#17: Table elimination
  - Add more testcases.
  - Remove handling of "column IN (one_element)".This is converted to equality 
    elsewhere

- Add an @@optimizer_switch flag for table_elimination for debug build
- Better comments 

mysql-test/t/index_merge_myisam.test:
  MWL#17: Table elimination: last fixes
  - Add an @@optimizer_switch flag for table_elimination for debug build
sql/mysql_priv.h:
  MWL#17: Table elimination: last fixes
  - Add an @@optimizer_switch flag for table_elimination for debug build
sql/mysqld.cc:
  MWL#17: Table elimination: last fixes
  - Add an @@optimizer_switch flag for table_elimination for debug build

- Correctly handle the case where we have multi-table DELETE and a table
  that we're deleting from looks like it could be eliminated.

- Remove a piece of code that's not needed anymore.

- More testcases
- Set correct dependencies for non-bound multi-equalities.

mysql-test/r/table_elim.result:
  MWL#17: Table elimination
  - More testcases
mysql-test/t/table_elim.test:
  MWL#17: Table elimination
  - More testcases
sql/opt_table_elimination.cc:
  MWL#17: Table elimination
  - Set correct dependencies for non-bound multi-equalities.

- Multiple-equality handling

- Use Table_elimination only for functional dependency checking for
  individual objects and rename it to Func_dep_analyzer

- Better comments
- Switch from "type" enum and switch to virtual functions for member funcs.

- Code cleanup

- Switch from trying to eliminate all tables at once (which didn't work)
  to the original approach of bottom-up elimination. 

- More testcases

- More dbug printouts
- More testcases

- More comments

- Better comments
- More OOM checks

sql/sql_select.cc:
  - Remove garbage code

- Add OOM error checking

- Address review feedback: change expression analyzer used to be a copy-paste
  of ref analyzer. ref analyzer, besides doing ref analysis, also collected 
  info about keys which had sargable predicates. We didn't need that part here.

- code cleanup

- Fix trivial valgrind failures that shown up after review

- Review feedback, more variable renames 

Continue with addressing review feedback part two: 
- rename enum members
- add checking for out of memory errors on allocation

- Switch from uniform graph to bipartite graph with two kinds of nodes:
  "values" (tables and fields) and "modules" (t.col=func(...) equalities, 
  multi-equalities, unique keys, inner sides of outer joins).
- Rename functions, classes, etc.

- More function renames, added comments

- Better comments

sql/sql_select.cc:
  MWL#17: Table elimination
  - Fix buildbot failure: do set correct value to nested_join::n_tables

Fixes after post-review fixes:
- Don't search for tables in JOIN_TAB array. it's not initialized yet.
  use select_lex->leaf_tables instead.

- Post-postreview changes fix: Do set NESTED_JOIN::n_tables to number of 
  tables left after elimination.

- When making inferences "field is bound" -> "key is bound", do check 
  that the field is part of the key

- Continue addressing review feedback: remove "unusable KEYUSEs" 
  extension as it is no longer needed.

sql/item.h:
  MWL#17: Table elimination
  - Code cleanup
sql/opt_table_elimination.cc:
  MWL#17: Table elimination
  - Code cleanup

Address review feedback: 
- Change from Wave-based approach (a-la const table detection) to 
  building and walking functional dependency graph.
- Change from piggy-backing on ref-access code and KEYUSE structures
  to using our own expression analyzer.


sql/item.cc:
  MWL#17: Table elimination
  - Move from C-ish Field_processor_info to C++ ish and generic Field_enumerator
sql/item.h:
  MWL#17: Table elimination
  - Move from C-ish Field_processor_info to C++ ish and generic Field_enumerator
sql/sql_bitmap.h:
  MWL#17: Table elimination
  - Backport of Table_map_iterator from 6.0