Make INSTALL_DOC option from streamlog available globally

CMakeLists.txt

@@ -14,6 +14,7 @@ SET( ${PROJECT_NAME}_VERSION_MAJOR 1 )
 SET( ${PROJECT_NAME}_VERSION_MINOR 6 )
 SET( ${PROJECT_NAME}_VERSION_PATCH 1 )
 
+OPTION( INSTALL_DOC "Set to OFF to skip build/install Documentation" ON )
 
 LIST( APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmakemodules" )
 INCLUDE( ilcsoft_default_settings )
@@ -36,7 +37,7 @@ ExternalProject_Add( cmakemodules
 
 ExternalProject_Add( streamlog
     SOURCE_DIR "${PROJECT_SOURCE_DIR}/streamlog"
-    CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX} -DCMAKE_MODULE_PATH=${PROJECT_SOURCE_DIR}/cmakemodules -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD} -DUSE_CXX11=${USE_CXX11}
+    CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX} -DCMAKE_MODULE_PATH=${PROJECT_SOURCE_DIR}/cmakemodules -DCMAKE_CXX_STANDARD=${CMAKE_CXX_STANDARD} -DUSE_CXX11=${USE_CXX11} -DINSTALL_DOC=${INSTALL_DOC}
     INSTALL_COMMAND ${CMAKE_BUILD_TOOL} install
 )