解决Golang（WINDOWS平台)调用openssl X509_STORE_load_locations函数时无法传递NULL指针导致该函数返回失败。

PS:Linux平台无此问题。

crypto/x509/x509_d2.c

@@ -86,6 +86,13 @@ int X509_STORE_load_locations(X509_STORE *ctx, const char *file,
                               const char *path)
 {
     X509_LOOKUP *lookup;
+    
+    //Support Go: 
+    //Go调用此函数无法传递NULL指针,只能传递空串。
+    if (file && *file == '\0')
+	file = NULL; 
+    if (path && *path == '\0')
+	path = NULL 	
 
     if (file != NULL) {
         lookup = X509_STORE_add_lookup(ctx, X509_LOOKUP_file());