zigbee_wrapper: Do IEEE754 test at runtime

zigbee_wrapper: Do IEEE754 test at runtime

Some systems (Tizen) havent __STDC_IEC_559__ defined
while sizeof(double) = 8, build breaks.

Moving test to run time is more flexible

For the record:
  BUILD_ID=tizen-ivi_20170328.2_ivi-target-odroidxu3
  gcc -dM -E - < /dev/null | grep 559
  #define __GCC_IEC_559_COMPLEX 0
  #define __GCC_IEC_559 0

Change-Id: I427188afcb6178e9a5e15c341185eb1b3d951fc8
Signed-off-by: Philippe Coval <philippe.coval@osg.samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/18333
Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: Joseph Morrow <joseph.l.morrow@intel.com>
Tested-by: Joseph Morrow <joseph.l.morrow@intel.com>