Fortran: Add code gen for do,concurrent's LOCAL/LOCAL_INIT [PR101602]

Fortran: Add code gen for do,concurrent's LOCAL/LOCAL_INIT [PR101602]

Implement LOCAL and LOCAL_INIT; we locally replace the tree declaration by
a local declaration of the outer variable. The 'local_init' then assigns
the value at the beginning of each loop iteration from the outer
declaration.

Note that the current implementation does not handle LOCAL with types that
have a default initializer and LOCAL/LOCAL_INIT for assumed-shape arrays;
this is diagnosed with a sorry error.

	PR fortran/101602

gcc/fortran/ChangeLog:

	* resolve.cc (resolve_locality_spec): Remove 'sorry, unimplemented'.
	* trans-stmt.cc (struct symbol_and_tree_t): New.
	(gfc_trans_concurrent_locality_spec): New.
	(gfc_trans_forall_1): Call it; update to handle local and local_init.
	* trans-decl.cc (gfc_start_saved_local_decls,
	gfc_stop_saved_local_decls): New; moved code from ...
	(gfc_process_block_locals): ... here. Call it.
	* trans.h (gfc_start_saved_local_decls,
	gfc_stop_saved_local_decls): Declare.

gcc/testsuite/ChangeLog:

	* gfortran.dg/do_concurrent_8_f2023.f90: Update for removed 'sorry,
	unimplemented'.
	* gfortran.dg/do_concurrent_9.f90: Likewise.
	* gfortran.dg/do_concurrent_all_clauses.f90: Likewise.
	* gfortran.dg/do_concurrent_local_init.f90: Likewise.
	* gfortran.dg/do_concurrent_locality_specs.f90: Likewise.
	* gfortran.dg/do_concurrent_11.f90: New test.
	* gfortran.dg/do_concurrent_12.f90: New test.
	* gfortran.dg/do_concurrent_13.f90: New test.
	* gfortran.dg/do_concurrent_14.f90: New test.
	* gfortran.dg/do_concurrent_15.f90: New test.