Fortran: associate to a contiguous pointer or target [PR122977]

Fortran: associate to a contiguous pointer or target [PR122977]

	PR fortran/122977

gcc/fortran/ChangeLog:

	* expr.cc (gfc_is_simply_contiguous): For an associate variable
	check whether the associate target is contiguous.
	* resolve.cc (resolve_symbol): Skip array type check for an
	associate variable when	the target has the contiguous attribute.

gcc/testsuite/ChangeLog:

	* gfortran.dg/contiguous_16.f90: New test.