Fortran: Fix recursive PDT function invocation [PR122433, PR122434]

Fortran: Fix recursive PDT function invocation [PR122433, PR122434]

2025-10-29  Paul Thomas  <pault@gcc.gnu.org>

gcc/fortran
	PR fortran/122433
	* decl.cc (gfc_get_pdt_instance): Prevent a PDT component of
	the same type as the template from being converted into an
	instance.

	PR fortran/122434
	* resolve.cc (gfc_impure_variable): The result of a pure
	function is a valid allocate object since it is pure.

gcc/testsuite/
	PR fortran/122433
	* gfortran.dg/pdt_62.f03: New test.

	PR fortran/122434
	* gfortran.dg/pdt_63.f03: New test.