enable LOG_LEVEL build option which can filter log in build time.

enable LOG_LEVEL build option which can filter log in build time.

Lite Device has always requirement to reduce memory size.
Also LOGGING build option is not enough for the requirement.
Thru, we need to provide to select log which can include in binary.

ex)
LOGGING=true -> about 2267kbyte (libconnectivity_abstraction,
                                 liboctbstack, libocsrm,
                                 libroutingmanager)
LOGGING=true LOG_LEVEL=ERROR -> 2184kbyte

=> about 82kbyte saving

Change-Id: I1158de8739b2cd8fa961ad6fc3ff8899c410cbce
Signed-off-by: jihwan.seo <jihwan.seo@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/17719
Tested-by: jenkins-iotivity <jenkins@iotivity.org>
Reviewed-by: Dan Mihai <Daniel.Mihai@microsoft.com>