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.

gdb/ui-out.h

@@ -145,6 +145,10 @@ class ui_out
   bool query_table_field (int colno, int *width, int *alignment,
 			  const char **col_name);
 
+  /* Return true if this stream is prepared to handle style
+     escapes.  */
+  virtual bool can_emit_style_escape () const = 0;
+
  protected:
 
   virtual void do_table_begin (int nbrofcols, int nr_rows, const char *tblid)