allow omp4 to be turned off

CMakeLists.txt

@@ -80,6 +80,7 @@ if (MORSE_DISTRIB_DIR OR EXISTS "${CMAKE_SOURCE_DIR}/CMakeModules/morse/")
     option( OPENMP_SUPPORT_COMMUTE   "Set to ON to let tasks commute (KSTAR/StarPU compiler only)" OFF )
     option( SCALFMM_USE_STARPU  "Set to ON to build SCALFMM with StarPU" OFF )
     option( SCALFMM_BUILD_UTILS "Set to ON to build utils Tests"    OFF )
+    option( SCALFMM_DISABLE_NATIVE_OMP4 "Set to ON to disable the gcc/intel omp4"    OFF )
   endif()
   if( SCALFMM_USE_MPI )
     try_compile(COMPILE_INTEL ${CMAKE_CURRENT_BINARY_DIR}

Src/ScalFmmConfig.h.cmake

@@ -65,6 +65,7 @@
 ///////////////////////////////////////////////////////
 
 #cmakedefine SCALFMM_USE_STARPU
+#cmakedefine SCALFMM_DISABLE_NATIVE_OMP4
 
 ///////////////////////////////////////////////////////
 // SSE

Src/Utils/FGlobal.hpp

@@ -99,7 +99,7 @@ typedef long long MortonIndex;
 // Test OMP4
 ///////////////////////////////////////////////////////
 
-#if _OPENMP >= 201307
+#if _OPENMP >= 201307 && !defined(SCALFMM_DISABLE_NATIVE_OMP4)
 #ifndef __INTEL_COMPILER
 #define SCALFMM_USE_OMP4
 #endif