pgsql: Create a stack of pl/python "execution contexts".

Create a stack of pl/python "execution contexts".

This replaces the former global variable PLy_curr_procedure, and provides
a place to stash per-call-level information. In particular we create a
per-call-level scratch memory context.

For the moment, the scratch context is just used to avoid leaking memory
from datatype output function calls in PLyDict_FromTuple. There probably
will be more use-cases in future.

Although this is a fix for a pre-existing memory leakage bug, it seems
sufficiently invasive to not want to back-patch; it feels better as part
of the major rearrangement of plpython code that we've already done as
part of 9.2.

Jan Urbański

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/ed75380bdae30dc1313aef44beafad860cf246c0

Modified Files
--------------
src/pl/plpython/plpy_cursorobject.c | 7 ++-
src/pl/plpython/plpy_elog.c | 8 ++-
src/pl/plpython/plpy_exec.c | 8 ++-
src/pl/plpython/plpy_main.c | 114 +++++++++++++++++++++++++++-------
src/pl/plpython/plpy_main.h | 15 +++++
src/pl/plpython/plpy_procedure.c | 3 -
src/pl/plpython/plpy_procedure.h | 4 -
src/pl/plpython/plpy_spi.c | 8 ++-
src/pl/plpython/plpy_typeio.c | 14 ++++
9 files changed, 141 insertions(+), 40 deletions(-)