message: revert back to ispc v1.9.2 for Linux binary releases
  NOTE: ispc v1.10.0 binary releases are not CentOS 6 compatible
diff: @@ -53,9 +53,9 @@ DEP_DIR=$ROOT_DIR/deps
  DEP_LOCATION=http://sdvis.org/ospray/download/dependencies/linux
  DEP_EMBREE=embree-3.4.0.x86_64.linux
  -DEP_ISPC_VER=1.10.0
  +DEP_ISPC_VER=1.9.2
  DEP_ISPC=ispc-v${DEP_ISPC_VER}-linux
  -DEP_ISPC_DIR=ispc-${DEP_ISPC_VER}-Linux
  +DEP_ISPC_DIR=ispc-${DEP_ISPC_VER}-linux
  DEP_TBB=tbb2019_20181203oss
  DEP_OIDN=oidn-0.8.0.x86_64.linux
  DEP_TARBALLS="$DEP_EMBREE.tar.gz $DEP_ISPC.tar.gz ${DEP_TBB}_lin.tgz $DEP_OIDN.tar.gz"
  @@ -98,7 +98,7 @@ cmake \
  -D OSPRAY_MODULE_MPI=ON \
  -D OSPRAY_MODULE_MPI_APPS=OFF \
  -D TBB_ROOT=$DEP_DIR/$DEP_TBB \
  --D ISPC_EXECUTABLE=$DEP_DIR/$DEP_ISPC_DIR/bin/ispc \
  +-D ISPC_EXECUTABLE=$DEP_DIR/$DEP_ISPC_DIR/ispc \
  -D OSPRAY_SG_CHOMBO=OFF \
  -D OSPRAY_SG_OPENIMAGEIO=OFF \
  -D OSPRAY_SG_VTK=OFF \
  