Bug#53251 mysql_library_init fails on second execution with embedded library

          thread-specific variables weren't set when we load error message files.

per-file comments:
  libmysqld/lib_sql.cc
Bug#53251      mysql_library_init fails on second execution with embedded library
      we need to call my_thread_init() once more. Normally it's called at the my_init()
      stage but that doesn't happen on the second my_init() call.

  sql/derror.cc
Bug#53251      mysql_library_init fails on second execution with embedded library
     use default errors for the embedded server.

  sql/mysqld.cc
Bug#53251      mysql_library_init fails on second execution with embedded library
        unregister server errors in clean_up(). Without it the error list contains
        that on the second mysql_server_init() which is not good.

  sql/set_var.cc
Bug#53251      mysql_library_init fails on second execution with embedded library
        sys_var::cleanup() call instead of the destructor

  sql/set_var.h
Bug#53251      mysql_library_init fails on second execution with embedded library
        sys_var::cleanup() introduced instead of the destructor
        
  sql/sys_vars.h
Bug#53251      mysql_library_init fails on second execution with embedded library
        Sys_var_charptr::cleanup() implemented

1 files changed, 4 insertions, 0 deletions

diff --git a/libmysqld/lib_sql.cc b/libmysqld/lib_sql.cc
index 94927c590cf..7d61dbc55f4 100644
--- a/libmysqld/lib_sql.cc
+++ b/libmysqld/lib_sql.cc
@@ -481,6 +481,10 @@ int init_embedded_server(int argc, char **argv, char **groups)
   char *fake_argv[] = { (char *)"", 0 };
   const char *fake_groups[] = { "server", "embedded", 0 };
   my_bool acl_error;
+
+  if (my_thread_init())
+    return 1;
+
   if (argc)
   {
     argcp= &argc;