we can't assume that because the send buffer is empty, no more data
can be expected. should still identify problems, as test will either
succeed or fail by the backend countdown timing out.

back ported from main SSL testsuite.

* patches/gtk2-main_iteration:
  GTK2: Fixed a few more uses of g_main_iteration().

glib 2.36 deprecated some stuff that the gtk-2 headerfiles use.
So set GLIB_VERSION_MIN_REQUIRED to a version prior to
GLIB_VERSION_2_36 to inhibit the deprecation warnings.

Fixes some deprecation warnings.

* patches/mariadb-conc-509:
  Configure [Mysql]: Survive MariaDB Connector/C 3.2.1 and later (CONC-509).

MariaDB Connector/C 3.2.1 CONC-509 changed the value returned
from mysql_get_client_version(3) from MYSQL_VERSION_ID to
MARIADB_PACKAGE_VERSION_ID.

Fixes support for MariaDB from 2021-05-31 and later.

* patches/bug10058:
  Configure: Improved exit(3C) C99 check.

Do not add C declarations behind #ifdef __cplusplus; it breaks
C++ compilers...

Fixes #10058 even more.

* patches/bug10058:
  Configure: Changed approach to autoconf 2.59 C99 kludge.

Always prepending a #include <stdlib.h> caused several tests
(eg AC_HAVE_FUNC) to fail due to mismatching prototypes.

Now we instead use the _AC_PROG_CXX_EXIT_DECLARATION kludge
also for C.

Fixes fall out from the previous fix for #10058.