x86: Add _CET_ENDBR to functions in crti.S

Add _CET_ENDBR to functions in crti.S, which are called indirectly, to
support IBT.

Tested on i686 and x86-64.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

	* sysdeps/i386/crti.S (_init): Add _CET_ENDBR.
	(_fini): Likewise.
	* sysdeps/x86_64/crti.S (_init): Likewise.
	(_fini): Likewise.