Update Linux Makefile
Update Linux Makefile

* When sample app source is updated in a working copy which was
  already built, make recognizes the change and rebuilds the
  app. Previously we had to run "make cleanall" and rebuild.
* When server_introspection.dat.h is updated, make recognizes
  the change and rebuilds the libraries and samples. This is
  handy while working with the DeviceBuilder based toolset to
  generate and supply new introspection data.

Change-Id: I4e69cc4e811b4e26dd126d8acaf385cc78ab06cd
Signed-off-by: Kishen Maloor <c62ddea3cd661a9268bff15f07fc2229cdc9ac02@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/26671
Tested-by: IoTivity Jenkins <6267f6022d49a8a37a7fe97da24aebfab797522c@iotivity.org>

iotivity/iotivity-constrained,iotivity/iotivity-constrained,iotivity/iotivity-constrained,iotivity/iotivity-constrained