Fix #81543: parse_url omits leading slash in windows paths

According to the RFC8089 Section 2[1]:

> The generic syntax in [RFC3986] includes "path" and "authority"
  components, for each of which only a subset is used in the definition
  of the file URI scheme.  The relevant subset of "path" is "path-
  absolute"

'path-absolute' in RFC3986 is defined as beginning with a '/' character.

There's also a requirement in RFC3986 section 3.3 [2], that

> If a URI contains an authority component, then the path component
  must either be empty or begin with a slash ("/") character.

For file:///c:/ URL the authority component is present but empty,
which implies 'localhost'. Thus the 'path' component must begin
with the '/' character.

For all intents and purposes 'file:///c:/' and 'file://localhost/c:/'
URLs are equivalent, so parsing them differently is a surprising behaviour.

Other popular languages like Java or JavaScript preserve the
leading slash character as well.

This effectively reverts commit [3].

[1] https://datatracker.ietf.org/doc/html/rfc8089#section-2
[2] https://datatracker.ietf.org/doc/html/rfc3986#section-3.3
[3] 4505a61

Author: Petr Pchelko

ext/standard/tests/url/parse_url_basic_001.phpt

@@ -806,7 +806,7 @@ echo "Done";
   ["scheme"]=>
   string(4) "file"
   ["path"]=>
-  string(3) "a:/"
+  string(4) "/a:/"
 }
 
 --> file:///ab:/: array(2) {
@@ -820,14 +820,14 @@ echo "Done";
   ["scheme"]=>
   string(4) "file"
   ["path"]=>
-  string(3) "a:/"
+  string(4) "/a:/"
 }
 
 --> file:///@:/: array(2) {
   ["scheme"]=>
   string(4) "file"
   ["path"]=>
-  string(3) "@:/"
+  string(4) "/@:/"
 }
 
 --> file:///:80/: array(2) {

ext/standard/tests/url/parse_url_basic_007.phpt

@@ -95,10 +95,10 @@ echo "Done";
 --> http://?:/   : bool(false)
 --> http://@?:/   : bool(false)
 --> file:///:   : string(2) "/:"
---> file:///a:/   : string(3) "a:/"
+--> file:///a:/   : string(4) "/a:/"
 --> file:///ab:/   : string(5) "/ab:/"
---> file:///a:/   : string(3) "a:/"
---> file:///@:/   : string(3) "@:/"
+--> file:///a:/   : string(4) "/a:/"
+--> file:///@:/   : string(4) "/@:/"
 --> file:///:80/   : string(5) "/:80/"
 --> []   : string(2) "[]"
 --> http://[x:80]/   : string(1) "/"

ext/standard/tests/url/parse_url_unterminated.phpt

@@ -812,7 +812,7 @@ echo "Done";
   ["scheme"]=>
   string(4) "file"
   ["path"]=>
-  string(3) "a:/"
+  string(4) "/a:/"
 }
 
 --> file:///ab:/: array(2) {
@@ -826,14 +826,14 @@ echo "Done";
   ["scheme"]=>
   string(4) "file"
   ["path"]=>
-  string(3) "a:/"
+  string(4) "/a:/"
 }
 
 --> file:///@:/: array(2) {
   ["scheme"]=>
   string(4) "file"
   ["path"]=>
-  string(3) "@:/"
+  string(4) "/@:/"
 }
 
 --> file:///:80/: array(2) {

ext/standard/url.c

@@ -167,12 +167,7 @@ PHPAPI php_url *php_url_parse_ex2(char const *str, size_t length, bool *has_port
 				s = e + 3;
 				if (zend_string_equals_literal_ci(ret->scheme, "file")) {
 					if (e + 3 < ue && *(e + 3) == '/') {
-						/* support windows drive letters as in:
-						   file:///c:/somedir/file.txt
-						*/
-						if (e + 5 < ue && *(e + 5) == ':') {
-							s = e + 4;
-						}
+						/* support file:/// */
 						goto just_path;
 					}
 				}