x86: Default CET run-time support to auto

CET has been added since GCC 8.  This patch defaults CET run-time support
to auto.  It enables CET run-time support if asssembler supports CET
instructions and multi-byte NOPs are enabled via SSE2.

config/

	* cet.m4 (GCC_CET_FLAGS): Change default to auto.

gcc/

	* configure: Regenerated.

libatomic/

	* configure: Regenerated.

libbacktrace/

	* configure: Regenerated.

libcc1/

	* configure: Regenerated.

libcpp/

	* configure: Regenerated.

libdecnumber/

	* configure: Regenerated.

libgcc/

	* configure: Regenerated.

libgfortran/

	* configure: Regenerated.

libgomp/

	* configure: Regenerated.

libitm/

	* configure: Regenerated.

libobjc/

	* configure: Regenerated.

libquadmath/

	* configure: Regenerated.

libsanitizer/

	* configure: Regenerated.

libssp/

	* configure: Regenerated.

libstdc++-v3/

	* configure: Regenerated.

libvtv/

	* configure: Regenerated.

zlib/

	* configure: Regenerated.

libcpp/ChangeLog

@@ -1,3 +1,7 @@
+2020-05-14  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* configure: Regenerated.
+
 2020-05-13  Jason Merrill  <jason@redhat.com>
 
 	* include/cpplib.h (enum c_lang): Change CXX2A to CXX20.