Abbreviate deprecated message

It appears that Doxygen cannot cope with macros with multiline
parameters.  There was a DEPRECATED macro with a multiline comment
explaining which method to use instead, which led to Doxygen producing
a warning message and failing to produce the correct documentation. With
the message passed to the DEPRECATED macro abbreviated so that it fits
in one line, Doxygen can produce the correct documentation.

(There is only one instrument_cover_goals() method which takes a
goto_programt as its first parameter.)

Author: John Nonweiler

src/goto-instrument/cover.cpp

@@ -54,10 +54,7 @@ void instrument_cover_goals(
 /// \deprecated use instrument_cover_goals(goto_programt &goto_program,
 /// const cover_instrumenterst &instrumenters,
 /// message_handlert &message_handler, const irep_idt mode) instead
-DEPRECATED(
-  "use instrument_cover_goals(goto_programt &goto_program,"
-  "const cover_instrumenterst &instrumenters,"
-  "message_handlert &message_handler, const irep_idt mode) instead")
+DEPRECATED("use instrument_cover_goals(goto_programt &...) instead")
 void instrument_cover_goals(
   const symbol_tablet &symbol_table,
   goto_programt &goto_program,