S/390: Implement -mnop-mcount

S/390: Implement -mnop-mcount

On i386 the profiler call sequence always consists of 1 call
instruction, so -mnop-mcount generates a single nop with the same
length as a call. For S/390 longer sequences may be used in some
cases, so -mnop-mcount generates the corresponding amount of nops.

2018-07-16  Ilya Leoshkevich  <iii@linux.ibm.com>

	* config/s390/s390.c (s390_function_profiler): Generate nops
	instead of profiler call sequences.
	* config/s390/s390.opt: Add the new option.

2018-07-16  Ilya Leoshkevich  <iii@linux.ibm.com>

	* gcc.target/s390/mnop-mcount-m31-fpic.c: New testcase.
	* gcc.target/s390/mnop-mcount-m31-mzarch.c: New testcase.
	* gcc.target/s390/mnop-mcount-m31.c: New testcase.
	* gcc.target/s390/mnop-mcount-m64-mfentry.c: New testcase.
	* gcc.target/s390/mnop-mcount-m64.c: New testcase.

From-SVN: r262734