patch 7.4.1065

Problem:    Cannot use the "dll" options on MS-Windows.
Solution:   Support the options on all platforms.  Use the built-in name as
            the default, so that it's clear what Vim is looking for.

src/if_python.c

@@ -732,12 +732,7 @@ python_runtime_link_init(char *libname, int verbose)
     int
 python_enabled(int verbose)
 {
-#ifdef WIN3264
-    char *dll = DYNAMIC_PYTHON_DLL;
-#else
-    char *dll = *p_pydll ? (char *)p_pydll : DYNAMIC_PYTHON_DLL;
-#endif
-    return python_runtime_link_init(dll, verbose) == OK;
+    return python_runtime_link_init((char *)p_pydll, verbose) == OK;
 }
 
 /*