Fix formatting buglet in python.c

python.c has a split string that is missing a space.  There's also a
stray backslash in this code.

Reviewed-By: Tom de Vries <tdevries@suse.de>

gdb/python/python.c

@@ -1601,7 +1601,7 @@ gdbpy_print_stack (void)
 	      /* An error occurred computing the string representation of the
 		 error message.  */
 	      gdb_printf (gdb_stderr,
-			  _("Error occurred computing Python error" \
+			  _("Error occurred computing Python error "
 			    "message.\n"));
 	      PyErr_Clear ();
 	    }