Fix cmake build

CMakeLists.txt

@@ -152,6 +152,7 @@ set( SOURCES src/config.c
              src/separator/separator.c
              src/tint2rc.c
              src/util/area.c
+             src/util/bt.c
              src/util/common.c
              src/util/fps_distribution.c
              src/util/strnatcmp.c

src/tint2conf/CMakeLists.txt

@@ -20,6 +20,7 @@ include_directories( ../util
                      ${RSVG_INCLUDE_DIRS} )
 
 set(SOURCES ../util/common.c
+            ../util/bt.c
             ../util/strnatcmp.c
             ../util/cache.c
             ../util/timer.c