Expand the ZEND_STRL macro to handle platforms where strncmp() is a macro.

On most platforms, this works fine, but on Linux armhf, strncmp() is a macro
rather than a real function, ergo the macro expansion of ZEND_STRL doesn't
occur until after the compiler knows it needs three parameters for strncmp()
and we get a compile error.

Fixes the fix for bug #61697.