gdb: Add an overloaded ui_out::text accepting a const std::string &

gdb/ChangeLog:

	* ui-out.h (class ui_out): Add ui_out::text accepting a constant
	reference to a std::string.  Fix all callers using
	std::string::c_str.
	* ui-out.c (ui_out::text): Ditto.

gdb/ada-lang.c

@@ -11865,7 +11865,7 @@ print_mention_exception (struct breakpoint *b)
 	  {
 	    std::string info = string_printf (_("`%s' Ada exception"),
 					      c->excep_string.c_str ());
-	    uiout->text (info.c_str ());
+	    uiout->text (info);
 	  }
 	else
 	  uiout->text (_("all Ada exceptions"));
@@ -11881,7 +11881,7 @@ print_mention_exception (struct breakpoint *b)
 	    std::string info
 	      = string_printf (_("`%s' Ada exception handlers"),
 			       c->excep_string.c_str ());
-	    uiout->text (info.c_str ());
+	    uiout->text (info);
 	  }
 	else
 	  uiout->text (_("all Ada exceptions handlers"));

gdb/cli/cli-setshow.c

@@ -760,7 +760,7 @@ cmd_show_list (struct cmd_list_element *list, int from_tty)
 	      std::string prefixname = list->prefix->prefixname ();
 	      prefixname = (!list->prefix->is_prefix () ? ""
 			    : strstr (prefixname.c_str (), "show ") + 5);
-	      uiout->text (prefixname.c_str ());
+	      uiout->text (prefixname);
 	    }
 	  uiout->field_string ("name", list->name);
 	  uiout->text (":  ");

gdb/source.c

@@ -1394,7 +1394,7 @@ print_source_lines_base (struct symtab *s, int line, int stopline,
 	  if (iter > start)
 	    {
 	      std::string text (start, iter);
-	      uiout->text (text.c_str ());
+	      uiout->text (text);
 	    }
 	  if (*iter == '\r')
 	    {

gdb/thread.c

@@ -1977,7 +1977,7 @@ print_selected_thread_frame (struct ui_out *uiout,
 	  uiout->text ("[Switching to thread ");
 	  uiout->field_string ("new-thread-id", print_thread_id (tp));
 	  uiout->text (" (");
-	  uiout->text (target_pid_to_str (inferior_ptid).c_str ());
+	  uiout->text (target_pid_to_str (inferior_ptid));
 	  uiout->text (")]");
 	}
     }

gdb/ui-out.c

@@ -581,6 +581,12 @@ ui_out::text (const char *string)
   do_text (string);
 }
 
+void
+ui_out::text (const std::string &string)
+{
+  text (string.c_str ());
+}
+
 void
 ui_out::call_do_message (const ui_file_style &style, const char *format,
 			 ...)

gdb/ui-out.h

@@ -203,6 +203,7 @@ class ui_out
 
   void spaces (int numspaces);
   void text (const char *string);
+  void text (const std::string &string);
 
   /* Output a printf-style formatted string.  In addition to the usual
      printf format specs, this supports a few GDB-specific