fixed alternate form for 'x' and 'X' formats

same fix exists in original code:
https://svn.apache.org/viewvc?view=revision&revision=1152309
Merge branch 'PHP-5.4' into PHP-5.5
Merge branch 'PHP-5.5'
different OSes have different messages, and that's not what the test is about anyway
fix bug #63982: isset() inconsistently produces a fatal error on protected property
Merge branch 'PHP-5.4' into PHP-5.5

* PHP-5.4:
  fix bug #63982: isset() inconsistently produces a fatal error on protected property
  different OSes have different messages, and that's not what the test is about anyway
Merge branch 'PHP-5.5'

* PHP-5.5:
  fix bug #63982: isset() inconsistently produces a fatal error on protected property
  different OSes have different messages, and that's not what the test is about anyway
Tinker with UPGRADING's wording for the format string changes for clarity.
Merge branch 'PHP-5.5'

* PHP-5.5:
  Tinker with UPGRADING's wording for the format string changes for clarity.