Adding librt on unix

openfpm_data @ 786671d4

-Subproject commit f2155a8fbf4d7f2a7787dc08861dca8f2d72093e
+Subproject commit 786671d4e191d7075ad539b0028e66ec93f4aeef

src/CMakeLists.txt

@@ -72,6 +72,9 @@ target_compile_features(pdata PUBLIC cxx_std_11)
 target_link_libraries(pdata ${MPI_C_LIBRARIES})
 target_link_libraries(pdata m)
 target_link_libraries(pdata c)
+if (UNIX)
+    target_link_libraries(pdata rt)
+endif (UNIX)
 
 install(FILES Decomposition/CartDecomposition.hpp 
 	      Decomposition/shift_vect_converter.hpp