pgsql: Avoid ecpglib core dump with out-of-order operations.

Avoid ecpglib core dump with out-of-order operations.

If an application executed operations like EXEC SQL PREPARE
without having first established a database connection, it could
get a core dump instead of the expected clean failure. This
occurred because we did "pthread_getspecific(actual_connection_key)"
without ever having initialized the TSD key actual_connection_key.
The results of that are probably platform-specific, but at least
on Linux it often leads to a crash.

To fix, add calls to ecpg_pthreads_init() in the code paths that
might use actual_connection_key uninitialized. It's harmless
(and hopefully inexpensive) to do that more than once.

Per bug #17514 from Okano Naoki. The problem's ancient, so
back-patch to all supported branches.

Discussion: /messages/by-id/17514-edd4fad547c5692c@postgresql.org

Branch
------
REL_11_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/f7797747fc8fa6e5d5513e6871ee56f7cf91c51c

Modified Files
--------------
src/interfaces/ecpg/ecpglib/connect.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)