IOT-2539 Fix write-strings warning
IOT-2539 Fix write-strings warning

The write-strings warning comes from assigning
the a const string to a char* that is not const.
From everything I see in this example the string
is not changed so simply using const_cast will
remove the warning.

If these values are always expected to be constant
we may want to consider changing the strutures
to hold const char * not char *. Without further
investigation I did not feel safe making that
change.

Bug: https://jira.iotivity.org/browse/IOT-2539
Change-Id: Ib9053a1041b72b1fd05329999efc7a7ff28aab94
Signed-off-by: George Nash <acbdc39d528a4315fe0b532d55c50ae46f5c1667@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/21753
Tested-by: jenkins-iotivity <d95b56ce41a2e1ac4cecdd398defd7414407cc08@iotivity.org>
Reviewed-by: Mats Wichmann <7a5e6f27299d2bbd9d04b59d9e8e4f8eab83d8cb@linux.com>
Reviewed-by: Phil Coval <ff46fec9739d31cce915aabcc3a7a2c00eee4d6c@osg.samsung.com>
Reviewed-by: Rick Bell <74cf0087f675c7c2d5c6f65986a0832071d4b512@intel.com>
(cherry picked from commit ff88390c2889d3e20bdbdcf73e10ada7584ab8e8)

rzr/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,rzr/iotivity,iotivity/iotivity,rzr/iotivity,rzr/iotivity,iotivity/iotivity,iotivity/iotivity,iotivity/iotivity