HPCC-16968 Problem with executing wutool

When wutool is built with USE_CPPUNIT enabled, it links to one of the plugins,
but this plugin is not patched up to refer to the appropriate install
directory.

Signed-off-by: Richard Chapman <rchapman@hpccsystems.com>

cmake_modules/commonSetup.cmake

@@ -894,7 +894,7 @@ IF ("${COMMONSETUP_DONE}" STREQUAL "")
   endif ( PLATFORM OR PLUGIN )
   set (CMAKE_SKIP_BUILD_RPATH  FALSE)
   set (CMAKE_BUILD_WITH_INSTALL_RPATH FALSE)
-  set (CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/${LIB_DIR}")
+  set (CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/${LIB_DIR};${CMAKE_INSTALL_PREFIX}/${PLUGINS_DIR}")
   set (CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
   if (APPLE)
     # used to locate libraries when compiling ECL