Closes GH-5295.

Closes GH-5758

Formerly, this had to be enabled by passing the configuration flag
`--enable-crt-debug`; now it can be enabled by setting the environment
variable `PHP_WIN32_DEBUG_HEAP`.  The advantage is that it is no longer
necessary to do separate builds, at the cost of a very minor
performance penalty during process startup.

This adds the following APIs:

void zend_call_known_function(
    zend_function *fn, zend_object *object, zend_class_entry *called_scope,
    zval *retval_ptr, int param_count, zval *params);

void zend_call_known_instance_method(
    zend_function *fn, zend_object *object, zval *retval_ptr, int param_count, zval *params);
void zend_call_known_instance_method_with_0_params(
    zend_function *fn, zend_object *object, zval *retval_ptr);
void zend_call_known_instance_method_with_1_params(
    zend_function *fn, zend_object *object, zval *retval_ptr, zval *param);
void zend_call_known_instance_method_with_2_params(
    zend_function *fn, zend_object *object, zval *retval_ptr, zval *param1, zval *param2);

These are used to perform a call if you already have the
zend_function you want to call. zend_call_known_function()
is the base API, the rest are just really thin wrappers around
it for the common case of instance method calls.

Closes GH-5692.

Closes GH-5676.

Closes GH-5673.

* PHP-7.4:
  Fix #79650: php-win.exe 100% cpu lockup

* PHP-7.3:
  Fix #79650: php-win.exe 100% cpu lockup

As of PHP 7.3.0, `sapi_cli_single_write()` is supposed to return `< 0`
on failure, but `fwrite()` returns a `size_t`, and signals error by
setting the stream's error indicator.  We have to cater to that.