Add more styling to "disassemble"

Add more styling to "disassemble"

This adds more styling to the disassemble command.  In particular,
addresses and function names in the disassembly are now styled.

This required fixing a small latent bug in set_output_style.  This
function always passed NULL to emit_style_escape; but when writing to
a file other than gdb_stdout, it should emit the style escape
directly.  (FWIW this is another argument for better integrating the
pager with ui_file and getting rid of this entire layer.)

gdb/ChangeLog
2019-08-06  Tom Tromey  <tom@tromey.com>

	* utils.c (set_output_style): Sometimes pass stream to
	emit_style_escape.
	* ui-out.h (class ui_out) <can_emit_style_escape>: Declare.
	* record-btrace.c (btrace_insn_history): Update.
	* mi/mi-out.h (class mi_ui_out) <can_emit_style_escape>: New
	method.
	* disasm.h (gdb_pretty_print_disassembler): Add uiout parameter.
	Update initializers.
	<m_uiout>: New field.
	<m_di>: Move lower.
	* disasm.c (gdb_pretty_print_disassembler::pretty_print_insn):
	Remove "uiout" parameter.
	(dump_insns): Update.
	* cli-out.h (class cli_ui_out) <can_emit_style_escape>: Declare.
	* cli-out.c (cli_ui_out::can_emit_style_escape): New method.

gdb/testsuite/ChangeLog
2019-08-06  Tom Tromey  <tom@tromey.com>

	* gdb.base/style.exp: Add disassemble test.
	* gdb.base/style.c (some_called_function): New function.
	(main): Use it.