i386: Remove _Unwind_Frames_Increment

CET kernel has been changed to place a restore token on shadow stack for
signal handler to enhance security.  It is usually transparent to user
programs since kernel will pop the restore token when signal handler
returns.  But when an exception is thrown from a signal handler, now
we need to remove _Unwind_Frames_Increment to pop the the restore token
from shadow stack.  Otherwise, we get

FAIL: g++.dg/torture/pr85334.C   -O0  execution test
FAIL: g++.dg/torture/pr85334.C   -O1  execution test
FAIL: g++.dg/torture/pr85334.C   -O2  execution test
FAIL: g++.dg/torture/pr85334.C   -O3 -g  execution test
FAIL: g++.dg/torture/pr85334.C   -Os  execution test
FAIL: g++.dg/torture/pr85334.C   -O2 -flto -fno-use-linker-plugin -flto-partition=none  execution test

	PR libgcc/85334
	* config/i386/shadow-stack-unwind.h (_Unwind_Frames_Increment):
	Removed.

From-SVN: r263030

libgcc/ChangeLog

+2018-07-27  H.J. Lu  <hongjiu.lu@intel.com>
+
+	PR libgcc/85334
+	* config/i386/shadow-stack-unwind.h (_Unwind_Frames_Increment):
+	Removed.
+
 2018-07-05  James Clarke  <jrtc27@jrtc27.com>
 
 	* configure: Regenerated.

libgcc/config/i386/shadow-stack-unwind.h

@@ -49,8 +49,3 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 	}					\
     }						\
     while (0)
-
-/* Increment frame count.  Skip signal frames.  */
-#undef _Unwind_Frames_Increment
-#define _Unwind_Frames_Increment(context, frames) \
-  if (!_Unwind_IsSignalFrame (context)) frames++