pgsql: Add test cases for indexam operations not currently covered.

Add test cases for indexam operations not currently covered.

That includes VACUUM on GIN, GiST and SP-GiST indexes, and B-tree indexes
large enough to cause page deletions in B-tree. Plus some other special
cases.

After this patch, the regression tests generate all different WAL record
types. Not all branches within the redo functions are covered, but it's a
step forward.

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/88fc71926392115cdc3672807f3903ce43d0ebcf

Modified Files
--------------
src/test/regress/expected/btree_index.out | 23 +++++++++++++
src/test/regress/expected/gin.out | 23 +++++++++++++
src/test/regress/expected/gist.out | 19 +++++++++++
src/test/regress/expected/spgist.out | 39 ++++++++++++++++++++++
src/test/regress/output/misc.source | 7 +++-
src/test/regress/parallel_schedule | 2 +-
src/test/regress/serial_schedule | 5 ++-
src/test/regress/sql/btree_index.sql | 28 ++++++++++++++++
src/test/regress/sql/gin.sql | 29 +++++++++++++++++
src/test/regress/sql/gist.sql | 25 +++++++++++++++
src/test/regress/sql/spgist.sql | 50 +++++++++++++++++++++++++++++
11 files changed, 247 insertions(+), 3 deletions(-)