[bugfix] Include config.h in lrutest.cc
This fixes a linker error for me. Without this patch I get:
rutest.cc:(.text._ZN3MPI9IntracommC2Ev[_ZN3MPI9IntracommC5Ev]+0x18): undefined reference to
MPI::Comm::Comm()' /usr/bin/ld: CMakeFiles/lrutest.dir/lrutest.cc.o: in function
MPI::Intracomm::Intracomm(ompi_communicator_t*)': lrutest.cc:(.text._ZN3MPI9IntracommC2EP19ompi_communicator_t[_ZN3MPI9IntracommC5EP19ompi_communicator_t]+0x2c): undefined reference toMPI::Comm::Comm()' /usr/bin/ld: CMakeFiles/lrutest.dir/lrutest.cc.o: in function
MPI::Op::Init(void ()(void const, void*, int, MPI::Datatype const&), bool)': lrutest.cc:(.text._ZN3MPI2Op4InitEPFvPKvPviRKNS_8DatatypeEEb[_ZN3MPI2Op4InitEPFvPKvPviRKNS_8DatatypeEEb]+0x2a): undefined reference toompi_mpi_cxx_op_intercept' /usr/bin/ld: CMakeFiles/lrutest.dir/lrutest.cc.o:(.data.rel.ro._ZTVN3MPI3WinE[_ZTVN3MPI3WinE]+0x48): undefined reference to
MPI::Win::Free()' /usr/bin/ld: CMakeFiles/lrutest.dir/lrutest.cc.o:(.data.rel.ro._ZTVN3MPI8DatatypeE[_ZTVN3MPI8DatatypeE]+0x78): undefined reference to `MPI::Datatype::Free()'