objdump/opcodes: add syntax highlighting to disassembler output

objdump/opcodes: add syntax highlighting to disassembler output

This commit adds the _option_ of having disassembler output syntax
highlighted in objdump.  This option is _off_ by default.  The new
command line options are:

  --disassembler-color=off		# The default.
  --disassembler-color=color
  --disassembler-color=extended-color

I have implemented two colour modes, using the same option names as we
use of --visualize-jumps, a basic 8-color mode ("color"), and an
extended 8bit color mode ("extended-color").

The syntax highlighting requires that each targets disassembler be
updated; each time the disassembler produces some output we now pass
through an additional parameter indicating what style should be
applied to the text.

As updating all target disassemblers is a large task, the old API is
maintained.  And so, a user of the disassembler (i.e. objdump, gdb)
must provide two functions, the current non-styled print function, and
a new, styled print function.

I don't currently have a plan for converting every single target
disassembler, my hope is that interested folk will update the
disassemblers they are interested in.  But it is possible some might
never get updated.

In this initial series I intend to convert the RISC-V disassembler
completely, and also do a partial conversion of the x86 disassembler.
Hopefully having the x86 disassembler at least partial converted will
allow more people to try this out easily and provide feedback.

In this commit I have focused on objdump.  The changes to GDB at this
point are the bare minimum required to get things compiling, GDB makes
no use of the styling information to provide any colors, that will
come later, if this commit is accepted.

This first commit in the series doesn't convert any target
disassemblers at all (the next two commits will update some targets),
so after this commit, the only color you will see in the disassembler
output, is that produced from objdump itself, e.g. from
objdump_print_addr_with_sym, where we print an address and a symbol
name, these are now printed with styling information, and so will have
colors applied (if the option is on).

Finally, my ability to pick "good" colors is ... well, terrible.  I'm
in no way committed to the colors I've picked here, so I encourage
people to suggest new colors, or wait for this commit to land, and
then patch the choice of colors.

I do have an idea about using possibly an environment variable to
allow the objdump colors to be customised, but I haven't done anything
like that in this commit, the color choices are just fixed in the code
for now.

binutils/ChangeLog:

	* NEWS: Mention new feature.
	* doc/binutils.texi (objdump): Describe --disassembler-color
	option.
	* objdump.c (disassembler_color): New global.
	(disassembler_extended_color): Likewise.
	(disassembler_in_comment): Likewise.
	(usage): Mention --disassembler-color option.
	(long_options): Add --disassembler-color option.
	(objdump_print_value): Use fprintf_styled_func instead of
	fprintf_func.
	(objdump_print_symname): Likewise.
	(objdump_print_addr_with_sym): Likewise.
	(objdump_color_for_disassembler_style): New function.
	(objdump_styled_sprintf): New function.
	(fprintf_styled): New function.
	(disassemble_jumps): Use disassemble_set_printf, and reset
	disassembler_in_comment.
	(null_styled_print): New function.
	(disassemble_bytes): Use disassemble_set_printf, and reset
	disassembler_in_comment.
	(disassemble_data): Update init_disassemble_info call.
	(main): Handle --disassembler-color option.

include/ChangeLog:

	* dis-asm.h (enum disassembler_style): New enum.
	(struct disassemble_info): Add fprintf_styled_func field, and
	created_styled_output field.
	(disassemble_set_printf): Declare.
	(init_disassemble_info): Add additional parameter.
	(INIT_DISASSEMBLE_INFO): Add additional parameter.

opcodes/ChangeLog:

	* dis-init.c (init_disassemble_info): Take extra parameter,
	initialize the new fprintf_styled_func and created_styled_output
	fields.
	* disassembler.c (disassemble_set_printf): New function definition.