(php-mode): Use setq rather than c-lang-defconst to support CC
Mode version 5.31 in Emacs 22.
(php-constants): "decomment" -> "uncomment".
(php-conditional-key): Delete constant.
(php-block-stmt-1-key, php-block-stmt-2-key): Generate from values
of php-block-stmt-1-kwds, php-block-stmt-2-kwds, respectively.
