Wrap help strings at 80 columns

This patch ensures that all ordinary help strings are wrapped at 80
columns.  For the most part this consists of changing code like this
(note the embedded \n and the trailing backslash without a newline):

-Manage the space-separated list of debuginfod server URLs that GDB will query \
-when missing debuginfo, executables or source files.\nThe default value is \
-copied from the DEBUGINFOD_URLS environment variable."),

... to end each line with \n\, like:

+Manage the space-separated list of debuginfod server URLs that GDB will\n\
+query when missing debuginfo, executables or source files.\n\
+The default value is copied from the DEBUGINFOD_URLS environment variable."),

Approved-By: Eli Zaretskii <eliz@gnu.org>

gdb/ada-lang.c

@@ -13957,11 +13957,11 @@ this option to \"off\" unless necessary."),
 
   add_setshow_boolean_cmd ("print-signatures", class_vars,
 			   &print_signatures, _("\
-Enable or disable the output of formal and return types for functions in the \
-overloads selection menu."), _("\
-Show whether the output of formal and return types for functions in the \
-overloads selection menu is activated."),
-			   NULL, NULL, NULL, &set_ada_list, &show_ada_list);
+Control the display of functions in overloads selection menu."), _("\
+Show how functions in overloads selection menu will be displayed."),
+			   _("\
+When enabled, formal and return types are shown."),
+			   NULL, NULL, &set_ada_list, &show_ada_list);
 
   ada_source_charset = gnat_source_charsets[0];
   add_setshow_enum_cmd ("source-charset", class_files,