shlwapi: Fix PathIsURL

[Huw D M Davies]

A test for this will follow

	Huw Davies <huw at codeweavers.com>
	PathIsURL should return TRUE even if a scheme is unknown.
Index: dlls/shlwapi/url.c
===================================================================
RCS file: /home/wine/wine/dlls/shlwapi/url.c,v
retrieving revision 1.40
diff -u -r1.40 url.c
--- dlls/shlwapi/url.c	4 Oct 2004 19:08:50 -0000	1.40
+++ dlls/shlwapi/url.c	4 Oct 2004 21:04:02 -0000
@@ -2078,7 +2078,7 @@
     /* get protocol        */
     base.cbSize = sizeof(base);
     res1 = ParseURLA(lpstrPath, &base);
-    return (base.nScheme > 0);
+    return (base.nScheme != URL_SCHEME_INVALID);
 }
 
 /*************************************************************************
@@ -2096,7 +2096,7 @@
     /* get protocol        */
     base.cbSize = sizeof(base);
     res1 = ParseURLW(lpstrPath, &base);
-    return (base.nScheme > 0);
+    return (base.nScheme != URL_SCHEME_INVALID);
 }
 
 /*************************************************************************