MDEV-22214 mariadbd.exe calls function mysqld.exe, and crashes

Stop linking plugins to the server executable on Windows.
Instead, extract whole server functionality into a large DLL, called
server.dll. Link both plugins, and small server "stub" exe to it.

This eliminates plugin dependency on the name of the server executable.
It also reduces the size of the packages (since tiny mysqld.exe
and mariadbd.exe are now both linked to one big DLL)

Also, simplify the functionality of exporing all symbols from selected
static libraries. Rely on WINDOWS_EXPORT_ALL_SYMBOLS, rather than old
self-backed solution.

fix compile error

replace GetProcAddress(GetModuleHandle(NULL), "variable_name")
for server exported data with actual variable names.

Runtime loading was never required,was error prone
, since symbols could be missing at runtime, and now it actually failed,
because we do not export symbols from executable anymore, but from a shared
library

This did require a MYSQL_PLUGIN_IMPORT decoration for the plugin,
but made the code more straightforward, and avoids missing symbols at
runtime (as mentioned before).

The audit plugin is still doing some dynamic loading, as it aims to work
cross-version. Now it won't work cross-version on Windows, as it already
uses some symbols that are *not* dynamically loaded, e.g fn_format
and those symbols now exported from server.dll , when earlier they were
exported by mysqld.exe

Windows, fixes for storage engine plugin loading
after various rebranding stuff

Create server.dll containing functionality of the whole server
make mariadbd.exe/mysqld.exe a stub that is only  calling mysqld_main()

fix build

sql/mysqld.h

@@ -117,7 +117,7 @@ extern bool opt_skip_name_resolve;
 extern bool opt_ignore_builtin_innodb;
 extern my_bool opt_character_set_client_handshake;
 extern my_bool debug_assert_on_not_freed_memory;
-extern bool volatile abort_loop;
+extern MYSQL_PLUGIN_IMPORT bool volatile abort_loop;
 extern Atomic_counter<uint> connection_count;
 extern my_bool opt_safe_user_create;
 extern my_bool opt_safe_show_db, opt_local_infile, opt_myisam_use_mmap;
@@ -143,7 +143,7 @@ extern ulong use_stat_tables;
 extern my_bool opt_old_style_user_limits, trust_function_creators;
 extern uint opt_crash_binlog_innodb;
 extern const char *shared_memory_base_name;
-extern char *mysqld_unix_port;
+extern MYSQL_PLUGIN_IMPORT char *mysqld_unix_port;
 extern my_bool opt_enable_shared_memory;
 extern ulong opt_replicate_events_marked_for_skip;
 extern char *default_tz_name;
@@ -168,7 +168,8 @@ extern my_bool relay_log_purge, opt_innodb_safe_binlog, opt_innodb;
 extern my_bool relay_log_recovery;
 extern uint select_errors,ha_open_options;
 extern ulonglong test_flags;
-extern uint protocol_version, mysqld_port, dropping_tables;
+extern uint protocol_version, dropping_tables;
+extern MYSQL_PLUGIN_IMPORT uint mysqld_port;
 extern ulong delay_key_write_options;
 extern char *opt_logname, *opt_slow_logname, *opt_bin_logname, 
             *opt_relay_logname;
@@ -281,7 +282,8 @@ extern handlerton *heap_hton;
 extern const char *load_default_groups[];
 extern struct my_option my_long_options[];
 int handle_early_options();
-extern int mysqld_server_started, mysqld_server_initialized;
+extern int MYSQL_PLUGIN_IMPORT mysqld_server_started;
+extern int mysqld_server_initialized;
 extern "C" MYSQL_PLUGIN_IMPORT int orig_argc;
 extern "C" MYSQL_PLUGIN_IMPORT char **orig_argv;
 extern pthread_attr_t connection_attrib;
@@ -752,8 +754,8 @@ extern mysql_mutex_t LOCK_start_thread;
 extern char* des_key_file;
 extern mysql_mutex_t LOCK_des_key_file;
 #endif
-extern mysql_mutex_t LOCK_server_started;
-extern mysql_cond_t COND_server_started;
+extern MYSQL_PLUGIN_IMPORT mysql_mutex_t LOCK_server_started;
+extern MYSQL_PLUGIN_IMPORT mysql_cond_t COND_server_started;
 extern mysql_rwlock_t LOCK_grant, LOCK_sys_init_connect, LOCK_sys_init_slave;
 extern mysql_rwlock_t LOCK_ssl_refresh;
 extern mysql_prlock_t LOCK_system_variables_hash;