Fixed Ubuntu having undefined references.

CMakeLists.txt

 set( CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmakemodules" )
 find_package( X11       REQUIRED )
 find_package( XExt      REQUIRED )
+find_package( RT        REQUIRED )
 
 set( CMAKE_CXX_FLAGS
      "${CMAKE_CXX_FLAGS} ${CMAKE_IMLIB2_CXX_FLAGS}" )
 
 # Includes
 include_directories( ${X11_INCLUDE_DIR}
-                     ${XEXT_INCLUDE_DIR} )
+                     ${XEXT_INCLUDE_DIR}
+                     ${RT_INCLUDE_DIR} )
 
 # Executable
 add_executable( "${BIN_TARGET}" ${source} )
 # Libraries
 target_link_libraries( "${BIN_TARGET}"
                        ${X11_LIBRARIES}
-                       "${XEXT_LIBRARY}" )
+                       "${XEXT_LIBRARY}"
+                       "${RT_LIBRARY}" )
 
 install( TARGETS ${BIN_TARGET}
          DESTINATION  ${CMAKE_INSTALL_PREFIX} )

cmakemodules/FindRT.cmake

+# - Find rt
+# Find the rt libraries, this is to fix ubuntu not having clock_gettime defined without it.
+#
+#  This module defines the following variables:
+#     RT_FOUND        - 1 if RT_INCLUDE_DIR & RT_LIBRARY are found, 0 otherwise
+#     RT_INCLUDE_DIR  - where to find Xlib.h, etc.
+#     RT_LIBRARY      - the X11 library
+#
+
+find_path( RT_INCLUDE_DIR
+           NAMES time.h )
+
+find_library( RT_LIBRARY
+              NAMES rt
+              PATHS /usr/lib /lib )
+
+if( RT_INCLUDE_DIR AND RT_LIBRARY )
+    set( RT_FOUND 1 )
+else()
+    set( RT_FOUND 0 )
+endif()
+
+mark_as_advanced( RT_INCLUDE_DIR RT_LIBRARY )

src/main.cpp

  * along with Slop.  If not, see <http://www.gnu.org/licenses/>.
  */
 #include <unistd.h>
+#include <time.h>
 #include <cstdio>
 #include <sstream>