Add latinime-common local lib

This is just a placeholder in this CL. It will be shared by LatinIME,
dicttool, and tests.

Change-Id: I6fb3516a5061555f6f24b29141c2871d2319b023
diff --git a/Android.mk b/Android.mk
index aa86911..17eeba8 100644
--- a/Android.mk
+++ b/Android.mk
@@ -12,5 +12,5 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-subdirs := native java tests tools
+subdirs := common native java tests tools
 include $(call all-named-subdir-makefiles, $(subdirs))