Made cmake handle MPI linking. Potentially a bad idea (usually better to use mpicc and mpicxx wrappers)

CMakeLists.txt

@@ -81,6 +81,11 @@ include_directories(src/common)                                # Common headers
 include_directories(${CMAKE_BINARY_DIR})                       # DSL headers
 include_directories(${CMAKE_CUDA_TOOLKIT_INCLUDE_DIRECTORIES}) # CUDA headers
 
+if (MPI_ENABLED)
+    find_package(MPI REQUIRED)
+    include_directories(${MPI_CXX_INCLUDE_DIRS})
+endif()
+
 ## Subdirectories
 add_subdirectory(src/utils)
 add_subdirectory(src/core/kernels)