re PR fortran/33288 (ICE (segfault) in mpfr_cmp2 when evaluating array initializers containing addition)

	PR fortran/33288

	* arith.c (reduce_unary, reduce_binary_ac, reduce_binary_ca,
	reduce_binary_aa): Call ourselves recursively if an element of
	the constructor is itself a constant array.

	* gfortran.dg/array_constructor_19.f90: New test.

From-SVN: r128632