BUG#11867985 - export symbols needed for auditing

include/m_ctype.h:
  Export symbols needed for auditing.
sql/mysqld.h:
  Export symbols needed for auditing.

include/m_ctype.h

@@ -346,7 +346,7 @@ extern CHARSET_INFO my_charset_utf32_bin;
 extern CHARSET_INFO my_charset_utf32_general_ci;
 extern CHARSET_INFO my_charset_utf32_unicode_ci;
 
-extern CHARSET_INFO my_charset_utf8_general_ci;
+extern MYSQL_PLUGIN_IMPORT CHARSET_INFO my_charset_utf8_general_ci;
 extern CHARSET_INFO my_charset_utf8_unicode_ci;
 extern CHARSET_INFO my_charset_utf8_bin;
 extern CHARSET_INFO my_charset_utf8mb4_bin;

sql/mysqld.h

@@ -73,7 +73,7 @@ void flush_thread_cache();
 void refresh_status(THD *thd);
 bool is_secure_file_path(char *path);
 
-extern MYSQL_PLUGIN_IMPORT CHARSET_INFO *system_charset_info;
+extern "C" MYSQL_PLUGIN_IMPORT CHARSET_INFO *system_charset_info;
 extern MYSQL_PLUGIN_IMPORT CHARSET_INFO *files_charset_info ;
 extern MYSQL_PLUGIN_IMPORT CHARSET_INFO *national_charset_info;
 extern MYSQL_PLUGIN_IMPORT CHARSET_INFO *table_alias_charset;
@@ -181,7 +181,8 @@ extern ulong opt_binlog_rows_event_max_size;
 extern ulong rpl_recovery_rank, thread_cache_size;
 extern ulong back_log;
 extern char language[FN_REFLEN];
-extern ulong server_id, concurrency;
+extern "C" MYSQL_PLUGIN_IMPORT ulong server_id;
+extern ulong concurrency;
 extern time_t server_start_time, flush_status_time;
 extern char *opt_mysql_tmpdir, mysql_charsets_dir[];
 extern int mysql_unpacked_real_data_home_len;
@@ -202,8 +203,8 @@ extern handlerton *heap_hton;
 extern const char *load_default_groups[];
 extern struct my_option my_long_options[];
 extern int mysqld_server_started;
-extern int orig_argc;
-extern char **orig_argv;
+extern "C" MYSQL_PLUGIN_IMPORT int orig_argc;
+extern "C" MYSQL_PLUGIN_IMPORT char **orig_argv;
 extern pthread_attr_t connection_attrib;
 extern MYSQL_FILE *bootstrap_file;
 extern my_bool old_mode;
@@ -306,7 +307,7 @@ extern uint mysql_real_data_home_len;
 extern const char *mysql_real_data_home_ptr;
 extern ulong thread_handling;
 extern MYSQL_PLUGIN_IMPORT char  *mysql_data_home;
-extern char server_version[SERVER_VERSION_LENGTH];
+extern "C" MYSQL_PLUGIN_IMPORT char server_version[SERVER_VERSION_LENGTH];
 extern MYSQL_PLUGIN_IMPORT char mysql_real_data_home[];
 extern char mysql_unpacked_real_data_home[];
 extern MYSQL_PLUGIN_IMPORT struct system_variables global_system_variables;