USER-INTEL: enforce icc and add icc flags

endif()

if(ENABLE_USER-INTEL)

    if (NOT CMAKE_CXX_COMPILER_ID STREQUAL "Intel")

      message(FATAL_ERROR "USER-INTEL is only useful together with intel compiler")

    endif()

    if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "2016")

      message(FATAL_ERROR "USER-INTEL is needed at least 2016 intel compiler")

    endif()

    if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "2017.3")

      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -xHost")

    else()

      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -xCOMMON-AVX512")

    endif()

    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -qopenmp -qno-offload -fno-alias -ansi-alias -restrict -DLMP_INTEL_USELRT -DLMP_USE_MKL_RNG-O2 -fp-model fast=2 -no-prec-div -qoverride-limits -qopt-zmm-usage=high") 

    set(USER-INTEL_SOURCES_DIR ${LAMMPS_SOURCE_DIR}/USER-INTEL)

    set(USER-INTEL_SOURCES ${USER-INTEL_SOURCES_DIR}/intel_preprocess.h

                           ${USER-INTEL_SOURCES_DIR}/intel_buffers.h