do not build SIRF-Contribs without Python

Fixes SyneRBI#448

SuperBuild.cmake

@@ -247,8 +247,11 @@ option(BUILD_pet_rd_tools "Build pet_rd_tools" OFF)
 option(BUILD_CIL "Build CCPi CIL Modules and ASTRA engine" OFF)
 option(BUILD_CIL_LITE "Build CCPi CIL Modules" OFF)
 option(BUILD_NIFTYREG "Build NIFTYREG" ON)
-option(BUILD_SIRF_Contribs "Build SIRF-Contribs" ON)
-
+if (BUILD_PYTHON)
+  option(BUILD_SIRF_Contribs "Build SIRF-Contribs" ON)
+else()
+  set(BUILD_SIRF_Contribs OFF CACHE BOOL "Build SIRF-Contribs" FORCE)
+endif()
 option(BUILD_SIRF_Registration "Build SIRFS's registration functionality" ${BUILD_NIFTYREG})
 if (BUILD_SIRF AND BUILD_SIRF_Registration AND NOT BUILD_NIFTYREG)
   message(WARNING "Building SIRF registration is enabled, but BUILD_NIFTYREG=OFF. Reverting to BUILD_NIFTYREG=ON")