The problem appears when we have a space followed by a non-format symbol.

Fix: properly skip spaces.


mysql-test/r/date_formats.result:
  Fix for bug #22029: str_to_date returning NULL, while date_format works using identical format.
    - test result.
mysql-test/t/date_formats.test:
  Fix for bug #22029: str_to_date returning NULL, while date_format works using identical format.
    - test case.
sql/item_timefunc.cc:
  Fix for bug #22029: str_to_date returning NULL, while date_format works using identical format.
    - skipping pre-spaces between each argument moved.