[petsc-dev] autogeneration of petscconf.h for C, C++ and Fortran

[Barry Smith]

   Currently BuildSystem generates a single petscconf.h that works for C, C++ and Fortran code. This unity came from the days before BuildSystem when we manually made this file.

   On occasion the same options in petscconf.h don't work for both C and C++ compilers, for example for __intel_fast_memcpy().  Should we instead generate three files one for each language?

    Barry