[trivial PATCH 12/22] [otp_mppe.c] eliminate build warnings

[Alan DeKok]

Frank Cusack wrote:
> Grouping 22 1-line patches into a single changeset is not large.  OTOH
> submitting them as 22 individual patches belies a naive understanding
> of source control, and actually makes merging that much more difficult,
> or at least time consuming.

  I also prefer changes to function prototypes to be in the same patch
as changes to the functions... otherwise the build breaks.

  Alan DeKok.