build: warnings as errors in jni code

build: warnings as errors in jni code

All build warnings have been cleaned from the
Java JNI code to make sure it continues to build
without warnings we are treating all warnings
as errors.

Change-Id: I05e7d75b81bed25b5f62ba353ff41ea28bca620a
Signed-off-by: George Nash <george.nash@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/21579
Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: Dan Mihai <Daniel.Mihai@microsoft.com>
Reviewed-by: Rick Bell <richard.s.bell@intel.com>
(cherry picked from commit de6a8023a209bfa316d329fa9b790310bde6ad81)
Reviewed-on: https://gerrit.iotivity.org/gerrit/22219
Reviewed-by: Larry Sachs <larry.j.sachs@intel.com>