Fortran: Fix regression caused by PR37336 patch [PR109209]

2023-03-21  Paul Thomas  <pault@gcc.gnu.org>

gcc/fortran
	PR fortran/109209
	* resolve.cc (generate_component_assignments): Restore the
	exclusion of allocatable components from the loop.

gcc/testsuite/
	PR fortran/109209
	* gfortran.dg/pr109209.f90: New test.