Fix linked libraries with CMake

Signed-off-by: Slávek Banko <slavek.banko@...>

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 89b2d99..ec3eb11 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -83,6 +83,12 @@
     tde_message_fatal( "libglade-2.0 are required, but not found on your system" )
 endif( NOT LIBGLADE_FOUND )
 
+
+set( EXTRA_LIBRARIES "-lm -lpthread" )
+if( UNIX )
+  set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fvisibility=hidden" )
+endif( UNIX )
+
 message( STATUS "Ready to build with backend ${BACKEND_NAME}" )
 
 
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 7d54add..7668568 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -40,7 +40,7 @@
   ${target} SHARED
   VERSION 0.0.0
   SOURCES ${${target}_SRCS}
-  LINK ${BACKEND_LIBS}
+  LINK ${BACKEND_LIBRARIES} ${ZLIB_LIBRARIES} ${EXTRA_LIBRARIES}
   DESTINATION ${LIB_INSTALL_DIR}
 )
 
@@ -48,7 +48,7 @@
   ${target} STATIC
   VERSION 0.0.0
   SOURCES ${${target}_SRCS}
-  LINK ${BACKEND_LIBS}
+  LINK ${BACKEND_LIBRARIES} ${ZLIB_LIBRARIES} ${EXTRA_LIBRARIES}
   DESTINATION ${LIB_INSTALL_DIR}
 )