aarch64: don't emit bti j after NOTE_INSN_DELETED_LABEL [PR94748]

It was previously discussed that indirect branches cannot go to
NOTE_INSN_DELETED_LABEL so inserting a landing pad is unnecessary.
See https://gcc.gnu.org/pipermail/gcc-patches/2019-May/522625.html

Before the patch a bti j was inserted after the label in

  __attribute__((target("branch-protection=bti")))
  int foo (void)
  {
  label:
    return 0;
  }

This is not necessary and weakens the security protection.

gcc/ChangeLog:

	PR target/94748
	* config/aarch64/aarch64-bti-insert.c (rest_of_insert_bti): Remove
	the check for NOTE_INSN_DELETED_LABEL.

gcc/testsuite/ChangeLog:

	PR target/94748
	* gcc.target/aarch64/pr94748.c: New test.