add RTLD_{NODELETE,NOLOAD,DEEPBIND}

[Jeff Johnson]

There are three additional dlopen flags in common usage but not in POSIX.

LSB should consider adding:

       RTLD_NODELETE (since glibc 2.2)
              Do not unload the library during dlclose(). Consequently, the
              library's static variables are not reinitialized if the library
              is reloaded with dlopen() at a later time. This flag is not
              specified in POSIX.1-2001.

       RTLD_NOLOAD (since glibc 2.2)
              Don't load the library. This can be used to test if the library
              is already resident (dlopen() returns NULL if it is not, or the
              library's handle if it is resident). This flag can also be used
              to promote the flags on a library that is already loaded. For
              example, a library that was previously loaded with RTLD_LOCAL
              can be reopened with RTLD_NOLOAD | RTLD_GLOBAL. This flag is
              not specified in POSIX.1-2001.

       RTLD_DEEPBIND (since glibc 2.3.4)
              Place the lookup scope of the symbols in this library ahead of
              the global scope. This means that a self-contained library will
              use its own symbols in preference to global symbols with the
              same name contained in libraries that have already been loaded.
              This flag is not specified in POSIX.1-2001.