bpo-28180: Fix the implementation of PEP 538 on Android (GH-4334)

diff --git a/Modules/readline.c b/Modules/readline.c
index 951bc82..d0e3b91 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -1245,7 +1245,7 @@
     char *saved_locale = strdup(setlocale(LC_CTYPE, NULL));
     if (!saved_locale)
         Py_FatalError("not enough memory to save locale");
-    setlocale(LC_CTYPE, "");
+    _Py_SetLocaleFromEnv(LC_CTYPE);
 #endif
 
     if (sys_stdin != rl_instream || sys_stdout != rl_outstream) {