S/390: Add support for arch<n> arch/tune options.

S/390: Add support for arch<n> arch/tune options.

This patch adds an alternate CPU level naming following the
architecture level number in the Principles of Operations manual.  So
instead of having z196, zEC12, and z13 you can use arch9, arch10, and
arch11.  The old cpu names stay valid and should preferably be used.

The alternate names are supposed to improve compatibility with the IBM
XL compiler toolchain which uses the arch numbering.

gcc/testsuite/ChangeLog:

2016-10-28  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* gcc.target/s390/target-attribute/tattr-m64-33.c: New test.

gcc/ChangeLog:

2016-10-28  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* config/s390/s390.opt: Support alternate cpu level naming (archXX).
	* config.gcc: Support alternate archXX cpu levels with
	--with-arch= and --with-tune=.
	* config/s390/linux.h: Translate new archXX cpu levels to the
	original names when calling GAS.
	* config/s390/tpf.h: Likewise.
	* doc/invoke.texi: Document the alternate cpu level names.

From-SVN: r241643