Fixed build issues under private linking for exported CMake targets.

Commit 158b6e1152413e4fa973b70b7469bb1f256a1f38[1] introduced a change
in tdecore/CMakeLists.txt (lines 140~149) to make private linking
for CMake targets.  This leads to the following build errors when I was
trying to update from TDE 14.0.7 to 14.0.9 here in Dragora
GNU/Linux-Libre[2].

The proposed change accommodates lines to pass ${XCOMPOSITE_LIBRARIES}
(-lXcomposite) when the presence of libXcomposite is detected, it also
accommodates ${KDESVGICONS} to circumvent the build error, leaving these
two variables out of the private linking statement.

[1] 158b6e1152
[2] http://ix.io/2OTG

Signed-off-by: Matías Fonzo <selk@dragora.org>

tdecore/CMakeLists.txt

@@ -142,10 +142,10 @@ tde_add_library( ${target} SHARED AUTOMOC
   SOURCES ${${target}_SRCS}
   VERSION 14.0.0
   EMBED tdecorenetwork-static ${TDEHW_LIB}
-  LINK DCOP-shared tdefx-shared ICE SM ${ZLIB_LIBRARIES}
-  LINK_PRIVATE ltdlc-static ${KDESVGICONS} ${XCOMPOSITE_LIBRARIES}
-    ${LIBIDN_LIBRARIES} ${LIBBFD_LIBRARIES} ${LIB_UTIL} ${GAMIN_LIBRARIES}
-    ${Backtrace_LIBRARY}
+  LINK ltdlc-static DCOP-shared tdefx-shared ICE SM ${ZLIB_LIBRARIES}
+    ${KDESVGICONS} ${XCOMPOSITE_LIBRARIES}
+  LINK_PRIVATE ${LIBIDN_LIBRARIES} ${LIBBFD_LIBRARIES} ${LIB_UTIL}
+    ${GAMIN_LIBRARIES} ${Backtrace_LIBRARY}
   DESTINATION ${LIB_INSTALL_DIR}
 )