OpenMP/Fortran: 'target update' with strides + DT components

OpenMP/Fortran: 'target update' with strides + DT components

OpenMP 5.0 permits to use arrays with strides and derived
type components for the list items to the 'from'/'to' clauses
of the 'target update' directive.

Partially committed to mainline as:

6629444170f85  OpenMP/Fortran: 'target update' with DT components

This patch contains the differences to the mainline version.

gcc/fortran/ChangeLog:

	* openmp.cc (resolve_omp_clauses): Apply to OpenMP target update.

libgomp/ChangeLog:

	* testsuite/libgomp.fortran/target-13.f90: Update test.