Add BUILD_STATIC option
Add BUILD_STATIC option

 - Enable BUILD_STATIC by default
 - If BUILD_STATIC and BUILD_SHARED are both different from 1, return an
error
 - If BUILD_STATIC is disabled, use shared library for binaries
 - If both are enabled, use the static library

Signed-off-by: Fabrice Fontaine <7d88633730b8b85c1516e612893df72eae9cd341@gmail.com>

intel/tinycbor,thiagomacieira/tinycbor,thiagomacieira/tinycbor,intel/tinycbor,01org/tinycbor,intel/tinycbor,intel/tinycbor,thiagomacieira/tinycbor,01org/tinycbor,thiagomacieira/tinycbor,01org/tinycbor