(debug_string_to_enum): Add DEBUG_INCREMENTAL).
* gold.cc (queue_initial_tasks): Check parameters for incremental link
mode.
* incremental.cc (report_command_line): Ignore all forms of
--incremental.
* layout.cc (Layout::Layout): Check parameters for incremental link
mode.
* options.cc (General_options::parse_incremental): New function.
(General_options::parse_no_incremental): New function.
(General_options::parse_incremental_full): New function.
(General_options::parse_incremental_update): New function.
(General_options::incremental_mode_): New data member.
(General_options::finalize): Check incremental_mode_.
* options.h (General_options): Update help text for --incremental.
Add --no-incremental, --incremental-full, --incremental-update.
(General_options::Incremental_mode): New enum type.
(General_options::incremental_mode): New function.
(General_options::incremental_mode_): New data member.
* parameters.cc (Parameters::incremental_mode_): New data member.
(Parameters::set_options): Set incremental_mode_.
(Parameters::set_incremental_full): New function.
(Parameters::incremental): New function.
(Parameters::incremental_update): New function.
(set_parameters_incremental_full): New function.
* parameters.h (Parameters::set_incremental_full): New function.
(Parameters::incremental): New function.
(Parameters::incremental_update): New function.
(Parameters::incremental_mode_): New data member.
(set_parameters_incremental_full): New function.
* plugin.cc (Plugin_manager::add_input_file): Check parameters for
incremental link mode.
* reloc.cc (Sized_relobj::do_read_relocs): Likewise.
(Sized_relobj::do_relocate_sections): Likewise.
* testsuite/Makefile.am (incremental_test): Use --incremental-full
option.
* testsuite/Makefile.in: Regenerate.
* testsuite/incremental_test.sh: Filter all forms of --incremental.
Alan Modra