Wrong array section bounds when passing to an intent-in pointer dummy.

Wrong array section bounds when passing to an intent-in pointer dummy.

Add code to allow for the creation a new descriptor for array
sections with the correct one based indexing.

Rework the generated descriptors indexing (hopefully) fixing the
wrong offsets generated.

gcc/fortran/ChangeLog:

2020-06-11  José Rui Faustino de Sousa  <jrfsousa@gmail.com>

	PR fortran/52351
	PR fortran/85868
	* trans-array.c (gfc_conv_expr_descriptor): Enable the
	creation of a new descriptor with the correct one based
	indexing for array sections.  Rework array descriptor
	indexing offset calculation.

gcc/testsuite/ChangeLog:

2020-06-11  José Rui Faustino de Sousa  <jrfsousa@gmail.com>

	PR fortran/52351
	PR fortran/85868
	* gfortran.dg/coarray_lib_comm_1.f90: Adjust match test for
	the newly generated descriptor.
	* gfortran.dg/PR85868A.f90: New test.
	* gfortran.dg/PR85868B.f90: New test.