Please GCC:

    In file included from /usr/include/php/20220829/Zend/zend.h:30,
                     from /usr/include/php/20220829/main/php.h:31,
                     from /usr/include/php/20220829/main/SAPI.h:20,
                     from src/php_snuffleupagus.h:37,
                     from src/sp_ifilter.c:1:
    src/sp_pcre_compat.h: In function 'sp_regexp_compile':
    src/sp_pcre_compat.h:38:36: warning: '__zend_calloc' sizes specified with 'sizeof' in the earlier argument and not in the later argument [-Wcalloc-transposed-args]
       38 |   sp_regexp *ret = pecalloc(sizeof(sp_regexp), 1, 1);
          |                                    ^~~~~~~~~
    /usr/include/php/20220829/Zend/zend_alloc.h:199:72: note: in definition of macro 'pecalloc'
      199 | #define pecalloc(nmemb, size, persistent) ((persistent)?__zend_calloc((nmemb), (size)):ecalloc((nmemb), (size)))
          |                                                                        ^~~~~
    src/sp_pcre_compat.h:38:36: note: earlier argument should specify number of elements, later size of each element
       38 |   sp_regexp *ret = pecalloc(sizeof(sp_regexp), 1, 1);
          |                                    ^~~~~~~~~
    /usr/include/php/20220829/Zend/zend_alloc.h:199:72: note: in definition of macro 'pecalloc'
      199 | #define pecalloc(nmemb, size, persistent) ((persistent)?__zend_calloc((nmemb), (size)):ecalloc((nmemb), (size)))
          |                                                                        ^~~~~

Avoid the configure step each time during development.

In addition of the current possibility to filter wrappers by their
protocol name, also add the option to filter the "php" wrapper by the
requested kind.
Especially the 'filter' backend can be disabled that way.

Not sure this is needed, but better safe than sorry.