HDF5 build: use -fno-strict-aliasing for MPICH

THis is per observed warning messages

Author: scivision

CMakeLists.txt

@@ -40,10 +40,15 @@ include(cmake/compilers.cmake)
 
 # if HDF5-MPI, ensure all the pieces are working together at configure time.
 if(hdf5_parallel)
+
+  set(MPI_DETERMINE_LIBRARY_VERSION true)
+
   find_package(MPI COMPONENTS C Fortran REQUIRED)
   include(cmake/check_mpi.cmake)
   check_mpi_version()
 
+  message(STATUS "MPI: ${MPI_Fortran_VERSION_STRING}")
+
   if(h5fortran_find)
     find_package(HDF5 COMPONENTS Fortran parallel)
   endif()

cmake/hdf5.cmake

@@ -104,6 +104,10 @@ set(hdf5_cmake_args
 # -DHDF5_USE_GNU_DIRS:BOOL=ON  # new for 1.14
 # -DHDF5_ENABLE_ZLIB_SUPPORT:BOOL=ON switched from -DHDF5_ENABLE_Z_LIB_SUPPORT:BOOL=ON for HDF5 2.0
 
+if(MPI_Fortran_LIBRARY_VERSION_STRING MATCHES "MPICH")
+  list(APPEND hdf5_cmake_flags "$<$<COMPILE_LANG_AND_ID:C,AppleClang,Clang,GNU,IntelLLVM>:-fno-strict-aliasing>")
+endif()
+
 if(MPI_ROOT)
   list(APPEND hdf5_cmake_args -DMPI_ROOT:PATH=${MPI_ROOT})
 endif()