mpi: Fix redefinition of types.
* mpi/mpi-internal.h (mpi_ptr_t): Remove, as it moved to mpi.h. (mpi_size_t): Likewise.
Cherry-pick master commit of:
85927387741fad2aba4f8cc01e3b10ff4ff4c57f
- Fixes-commit: 88ae76d069c331ad947ecab8419df9a00f979b0e
- GnuPG-bug-id: T7775
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>