php8: fix gettext and intl dependencies and build

php8: fix gettext and intl dependencies and build

* Add a needed BUILD_DEPENDENCY on icu package, when PHP8_INTL is
  defined.
* Make PHP8_DOM selecting PHP8_LIBXML instead of depending on it.
* PHP8_INTL does not depend on PHP8_GETTEXT, it builds also
  without gettext.
* Always show option for choosing PHP8_FULLUCIDATA
* For php8-cgi, php-cli, etc, a libstdcpp dependency is only gained
when PHP8_INTL is selected, therefore update those conditional depends.

As some combinations of these changes can change the binaries output,
PKG_RELEASE has been bumped.

Signed-off-by: Daniel F. Dickinson <dfdpublic@wildtechgarden.ca>
Signed-off-by: Michael Heimpold <mhei@heimpold.de>