[2.0.0] Constants workaround

I was unable to zephir generate on phalcon 2.0 source before those changes. Now the whole generation goes well but compilation is broken:

    libtool: compile:  gcc -I. -I/var/www/cphalcon/ext -DPHP_ATOM_INC -I/var/www/cphalcon/ext/include -I/var/www/cphalcon/ext/main -I/var/www/cphalcon/ext -I/usr/include/php5 -I/usr/include/php5/main -I/usr/include/php5/TSRM -I/usr/include/php5/Zend -I/usr/include/php5/ext -I/usr/include/php5/ext/date/lib -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -DHAVE_CONFIG_H -O2 -c /var/www/cphalcon/ext/phalcon/mvc/collection/manager.c  -fPIC -DPIC -o phalcon/mvc/collection/.libs/manager.o
    /var/www/cphalcon/ext/phalcon/mvc/collection/manager.c: In function 'zim_Phalcon_Mvc_Collection_Manager_initialize':
    /var/www/cphalcon/ext/phalcon/mvc/collection/manager.c:203:83: error: 'true' undeclared (first use in this function)
    /var/www/cphalcon/ext/phalcon/mvc/collection/manager.c:203:83: note: each undeclared identifier is reported only once for each function it appears in
    make: *** [phalcon/mvc/collection/manager.lo] Error 1