x86/CET: Add -fcf-protection to STAGE4_CFLAGS

Since profiledbootstrap uses

STAGEfeedback_CFLAGS = $(STAGE4_CFLAGS) -fprofile-use

add

STAGE4_CFLAGS += -fcf-protection -mcet

to bootstrap-cet.mk to support profiledbootstrap with CET.

	PR bootstrap/85490
	* bootstrap-cet.mk (STAGE4_CFLAGS): New.

From-SVN: r259620

config/ChangeLog

 2018-04-24  H.J. Lu  <hongjiu.lu@intel.com>
 
+	PR bootstrap/85490
+	* bootstrap-cet.mk (STAGE4_CFLAGS): New.
+
+2018-04-24  H.J. Lu  <hongjiu.lu@intel.com>
+
 	PR target/85485
 	* bootstrap-cet.mk (STAGE2_CFLAGS): Remove -mcet.
 	(STAGE3_CFLAGS): Likewise.

config/bootstrap-cet.mk

-# This option enables -fcf-protection for stage2 and stage3.
+# This option enables -fcf-protection for stage2, stage3 and stage4.
 
 STAGE2_CFLAGS += -fcf-protection
 STAGE3_CFLAGS += -fcf-protection
+STAGE4_CFLAGS += -fcf-protection