build: link dlopen libs with "nodelete"

This way a dlclose() will not unmap the libs memory anymore. A real
dlclose() will not work anyways because we lack destructors for all the
stuff we initialize in setup_descriptor->init().
Signed-off-by: Henning Schild <henning.schild@siemens.com>

configure.ac

@@ -685,6 +685,7 @@ AC_MSG_RESULT(${CONFIG_XENO_LIBS_DLOPEN:-no})
 if test x$CONFIG_XENO_LIBS_DLOPEN = xy; then
 	AC_DEFINE(CONFIG_XENO_LIBS_DLOPEN,1,[config])
 	AC_DEFINE_UNQUOTED(CONFIG_XENO_TLS_MODEL,"global-dynamic",[TLS model])
+	XENO_LIB_LDFLAGS="-Wl,-z -Wl,nodelete"
 else
 	AC_DEFINE_UNQUOTED(CONFIG_XENO_TLS_MODEL,"initial-exec",[TLS model])
 	XENO_LIB_LDFLAGS="-Wl,-z -Wl,nodlopen"