GeezerVison

* gh-157649: Check for reference leak in test_cext (#158227)

test_cext now discovers and calls all "test" functions. On a debug
build, it also checks for reference leaks.

Fix a reference leak in test_virtual_object(): use a dealloc function
which calls Py_DECREF() on the type, and trigger an explicit garbage
collection.

(cherry picked from commit 7952713)

* gh-149044: Build test_cext with -Wall -Wextra (#158867)

(cherry picked from commit b22a8c9)

…59314)

* [3.15] gh-157649: Check for reference leak in test_cext (#159296)

* gh-157649: Check for reference leak in test_cext (#158227)

test_cext now discovers and calls all "test" functions. On a debug
build, it also checks for reference leaks.

Fix a reference leak in test_virtual_object(): use a dealloc function
which calls Py_DECREF() on the type, and trigger an explicit garbage
collection.

(cherry picked from commit 7952713)

* gh-149044: Build test_cext with -Wall -Wextra (#158867)

(cherry picked from commit b22a8c9)
(cherry picked from commit 8514386)

* Fix refleak in test_datetime()

Only call PyDateTime_IMPORT once to initialize PyDateTimeAPI.