Convert init_ada_exception_catchpoint to a ctor

Currently, init_ada_exception_catchpoint is defined in breakpoint.c, I
presume so it can call the static describe_other_breakpoints function.
I think this is a dependency inversion.
init_ada_exception_catchpoint, being code specific to Ada catchpoints,
should be in ada-lang.c, and describe_other_breakpoints, a core
function, should be exported.

And then, we can convert init_ada_exception_catchpoint to an
ada_catchpoint ctor.

Change-Id: I07695572dabc5a75d3d3740fd9b95db1529406a1

gdb/breakpoint.h

@@ -1460,17 +1460,6 @@ extern void
 		     void *user_data_catch,
 		     void *user_data_tcatch);
 
-/* Initialize a breakpoint struct for Ada exception catchpoints.  */
-
-extern void
-  init_ada_exception_breakpoint (struct breakpoint *b,
-				 struct gdbarch *gdbarch,
-				 struct symtab_and_line sal,
-				 const char *addr_string,
-				 int tempflag,
-				 int enabled,
-				 int from_tty);
-
 /* Add breakpoint B on the breakpoint list, and notify the user, the
    target and breakpoint_created observers of its existence.  If
    INTERNAL is non-zero, the breakpoint number will be allocated from
@@ -1905,4 +1894,12 @@ extern void catch_exception_event (enum exception_event_kind ex_event,
 
 extern void print_solib_event (bool is_catchpoint);
 
+/* Print a message describing any user-breakpoints set at PC.  This
+   concerns with logical breakpoints, so we match program spaces, not
+   address spaces.  */
+
+extern void describe_other_breakpoints (struct gdbarch *,
+					struct program_space *, CORE_ADDR,
+					struct obj_section *, int);
+
 #endif /* !defined (BREAKPOINT_H) */