Enhance further testcases to verify Openacc 'kernels' decomposition

Enhance further testcases to verify Openacc 'kernels' decomposition

	gcc/testsuite/
	* c-c++-common/goacc-gomp/nesting-1.c: Enhance.
	* c-c++-common/goacc/kernels-loop-g.c: Likewise.
	* c-c++-common/goacc/nesting-1.c: Likewise.
	* gcc.dg/goacc/nested-function-1.c: Likewise.
	* gfortran.dg/goacc/common-block-3.f90: Likewise.
	* gfortran.dg/goacc/nested-function-1.f90: Likewise.
	libgomp/
	* testsuite/libgomp.oacc-c-c++-common/acc_prof-kernels-1.c:
	Enhance.
	* testsuite/libgomp.oacc-c-c++-common/kernels-loop-g.c: Likewise.
	* testsuite/libgomp.oacc-fortran/if-1.f90: Likewise.