[3.12] gh-53203: Fix strptime() for %c and %x formats on many locales (GH-124946...

[3.12] gh-53203: Fix strptime() for %c and %x formats on many locales (GH-124946) (GH-125370)

In some locales (like French or Hebrew) the full or abbreviated names of
the default month and weekday used in __calc_date_time can be part of
other name or constant part of the %c format. The month name can also
match %m with constant suffix (like in Japanese). So the code failed to
correctly distinguish formats %a, %A, %b, %B and %m.

Cycle all month and all days of the week to find the variable part
and distinguish %a from %A and %b from %B or %m.

Fixed locales for the following languges:
Arabic, Bislama, Breton, Bodo, Kashubian, Chuvash, Estonian, French, Irish,
Ge'ez, Gurajati, Manx Gaelic, Hebrew, Hindi, Chhattisgarhi, Haitian Kreyol,
Japanese, Kannada, Korean, Marathi, Malay, Norwegian, Nynorsk, Punjabi,
Rajasthani, Tok Pisin, Yoruba, Yue Chinese, Yau/Nungon and Chinese.

(cherry picked from commit c05f9dde8a12dfd63d3ade93da616042df2dc925)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>
Co-authored-by: Eli Bendersky <eliben@gmail.com>