Bug#38293 Libmysqld crash in mysql_library_init if language file missing

That's a Win-specific error.
    When we create libmysqld.dll we have many libraries like mysys, dbug,
    strings, etc linked into that dll, so the application built upon
    this library shouldn't link these libraries to itself, rather use
    those inside the dll.

    Fixed by redirecting calls into the libmysqld.dll

per-file comments:
  dbug/dbug.c
Bug#38293 Libmysqld crash in mysql_library_init if language file missing
    fake _db_something definitions added

  include/my_dbug.h
Bug#38293 Libmysqld crash in mysql_library_init if language file missing
  fake _db_something declarations added

  libmysqld/examples/CMakeLists.txt
Bug#38293 Libmysqld crash in mysql_library_init if language file missing
    superfluous libraries removed from linking

  libmysqld/libmysqld.def
Bug#38293 Libmysqld crash in mysql_library_init if language file missing
    set of mysys functions added to the export section

dbug/dbug.c

@@ -2407,4 +2407,13 @@ int i_am_a_dummy_function() {
        return 0;
 }
 
+#ifdef __WIN__
+char _db_doprnt_;
+char _db_enter_;
+char _db_pargs_;
+char _db_process_;
+char _db_push_;
+char _db_return_;
+#endif /*__WIN__*/
+
 #endif