buildroot

php: fix phar build failure for CLI

Disable the phar command-line tool since it requires php to pack itself
up. Fixes build failure for CLI (or CLI+CGI) variants of php.
Hardly useful for embedded scenarios.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>