python/19506 -- gdb.Breakpoint address location regression

Now that "legacy" linespecs benefit from consolidated support in
string_to_event_location_basic, python's Breakpoint command should use this
function to turn strings into event locations.

As a result, this patch fixes python/19506. Before:

(gdb) python gdb.Breakpoint("*main")
Traceback (most recent call last):
  File "<string>", line 1, in <module>
RuntimeError: Function "*main" not defined.
Error while executing Python code.

After:

(gdb) python gdb.Breakpoint("*main")
Breakpoint 1 at 0x4005fb: file ../../../src/gdb/testsuite/gdb.python/py-breakpoint.c, line 32.

gdb/ChangeLog

	PR python/19506
	* python/py-breakpoint.c (bppy_init): Use
	string_to_event_location_basic instead of new_linespec_location.

gdb/testsuite/ChangeLog

	PR python/19506
	* gdb.python/py-breakpoint.exp (test_bkpt_address): New procedure.
	(toplevel): Call test_bkpt_address.

gdb/python/py-breakpoint.c

@@ -663,7 +663,7 @@ bppy_init (PyObject *self, PyObject *args, PyObject *kwargs)
 
   TRY
     {
-      char *copy = xstrdup (spec);
+      char *copy = xstrdup (skip_spaces_const (spec));
       struct cleanup *cleanup = make_cleanup (xfree, copy);
 
       switch (type)
@@ -672,7 +672,8 @@ bppy_init (PyObject *self, PyObject *args, PyObject *kwargs)
 	  {
 	    struct event_location *location;
 
-	    location = new_linespec_location (&copy);
+	    location
+	      = string_to_event_location_basic (&copy, current_language);
 	    make_cleanup_delete_event_location (location);
 	    create_breakpoint (python_gdbarch,
 			       location, NULL, -1, NULL,