S390: Add configure check to detect support for arch13.

Add two configure checks which detect if arch13 is supported
by the assembler at all - by explicitely setting the machine -
and if it is supported with default settings.

ChangeLog:

	* config.h.in (HAVE_S390_MIN_ARCH13_ZARCH_ASM_SUPPORT,
	HAVE_S390_ARCH13_ASM_SUPPORT): New undefine.
	* sysdeps/s390/configure.ac: Add checks for arch13 support.
	* sysdeps/s390/configure: Regenerated.