s390: implement flags output

s390: implement flags output

Implement flags output for inline assemblies.  Only use one output constraint
that captures the whole condition code.  No breakout into different condition
codes is allowed.  Also, only one condition code variable is allowed.

Add further logic to canonicalize various cases where we combine different
cases of possible condition codes.

gcc/ChangeLog:

	* config/s390/s390-c.cc (s390_cpu_cpp_builtins): Define
	__GCC_ASM_FLAG_OUTPUTS__.
	* config/s390/s390.cc (s390_canonicalize_comparison): More
	UNSPEC_CC_TO_INT cases.
	(s390_md_asm_adjust): Implement flags output.
	* config/s390/s390.md (ccstore4): Allow mask operands.
	* doc/extend.texi: Document flags output.

gcc/testsuite/ChangeLog:

	* gcc.target/s390/ccor.c: New test.

Signed-off-by: Juergen Christ <jchrist@linux.ibm.com>