BUG (and fix) configuring with cmake

cmake does not configure RandomLib properly if it can't find boost.
The following patch fixes this. (RandomLib does not require boost.)

Index: examples/CMakeLists.txt

--- examples/CMakeLists.txt (revision 6940)
+++ examples/CMakeLists.txt (revision 6951)
@@ -1,6 +1,9 @@
# $Id$

-include_directories (${Boost_INCLUDE_DIRS})
+if (Boost_FOUND)
+ include_directories (${Boost_INCLUDE_DIRS})
+endif (Boost_FOUND)
+
add_custom_target (examples ALL)
foreach (EXAMPLE ${EXAMPLES})