With revision 259522:

commit d59cfa9a4064339cf2bd2da828c4c133f13e57f0
Author: hjl <hjl@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Fri Apr 20 13:30:13 2018 +0000

    Define __CET__ for -fcf-protection and remove -mibt

-mcet becomes an alias for -mshstk.

	PR target/85485
	* cet.m4 (GCC_CET_FLAGS): Replace -mcet with -mshstk.

From-SVN: r259608