Add qualifier 'const' to argument args

Add qualifier 'const' to argument args

This patch fixes the following error.

../../../git/gdb/gnu-nat.c: In function 'info_port_rights':
../../../git/gdb/gnu-nat.c:3083:11: error: passing argument 1 of 'parse_to_comma_and_eval' from incompatible pointer type [-Werror]
In file included from ../../../git/gdb/breakpoint.h:23:0,
                 from ../../../git/gdb/inferior.h:37,
                 from ../../../git/gdb/gnu-nat.c:55:
../../../git/gdb/value.h:763:22: note: expected 'const char **' but argument is of type 'char **'

gdb:

2014-01-07  Yao Qi  <yao@codesourcery.com>

	* gnu-nat.c (info_port_rights): Add qualifier const to
	argument args.