Fix calling convention of php_pcre_replace/php_replace_in_subject
Summary:
All call sites of php_pcre_replace were checking for a return of bool, asserting that it's false, and returning init_null instead. Change places in php_pcre_replace that return false to return ini_null instead and simplify the call sites.
php_replace_in_subject only ever returns string on init_null, so simplify call sites.
Reviewed By: ricklavoie
Differential Revision:
D24914966
fbshipit-source-id:
b37e5b0dd5d845badf1872fccdfae9f696db54bb