i386: Don't insert ENDBR after NOTE_INSN_DELETED_LABEL

i386: Don't insert ENDBR after NOTE_INSN_DELETED_LABEL

NOTE_INSN_DELETED_LABEL is used to mark what used to be a 'code_label',
but was not used for other purposes than taking its address which cannot
be used as target for indirect jumps.

Tested on Linux/x86-64 with -fcf-protection.

For x86-64 libc.so on glibc master branch (commit f43b8dd55588c3),

Before: 2961 endbr64
After:  2943 endbr64

gcc/

	PR target/89355
	* config/i386/i386-features.c (rest_of_insert_endbranch): Remove
	NOTE_INSN_DELETED_LABEL check.

gcc/testsuite/

	PR target/89355
	* gcc.target/i386/cet-label-3.c: New test.
	* gcc.target/i386/cet-label-4.c: Likewise.
	* gcc.target/i386/cet-label-5.c: Likewise.

Co-Authored-By: Hongtao Liu <hongtao.liu@intel.com>
From-SVN: r271828