Check for dynamic linking of Boost::Test library

BOOST_TEST_DYN_LINK must be defined if you are *building* Boost::Test as
a shared object, and the client programs must also include this option
when they use the header files, to link to it correctly.

cmake/Modules/UseDynamicBoost.cmake

@@ -0,0 +1,33 @@
+# be sure that this component is searched for
+find_package (Boost COMPONENTS unit_test_framework QUIET)
+
+if (${Boost_UNIT_TEST_FRAMEWORK_FOUND})
+  # setup to do a test compile
+  include (CMakePushCheckState)
+  cmake_push_check_state ()
+  include (CheckCXXSourceCompiles)
+  list (APPEND CMAKE_REQUIRED_INCLUDES ${Boost_INCLUDE_DIRS})
+  list (APPEND CMAKE_REQUIRED_LIBRARIES ${Boost_LIBRARIES})
+
+  check_cxx_source_compiles("
+#define BOOST_TEST_DYN_LINK
+#define BOOST_TEST_MODULE DYNLINK_TEST
+#include <boost/test/unit_test.hpp>
+
+int f(int x) { return 2 * x; }
+
+BOOST_AUTO_TEST_CASE(DynlinkConfigureTest) {
+  BOOST_CHECK_MESSAGE(f(2) == 4,
+                      \"Apparently, multiplication doesn't \"
+                      \"work: f(2) = \" << f(2));
+}" HAVE_DYNAMIC_BOOST_TEST)
+  cmake_pop_check_state ()
+else (${Boost_UNIT_TEST_FRAMEWORK_FOUND})
+  # no Boost, no compile
+  set (HAVE_DYNAMIC_BOOST_TEST 0)
+endif (${Boost_UNIT_TEST_FRAMEWORK_FOUND})
+
+# save this for later
+set (HAVE_DYNAMIC_BOOST_TEST "${HAVE_DYNAMIC_BOOST_TEST}"
+  CACHE BOOL "Whether Boost::Test is dynamically linked or not"
+  )