It is a minor issue. In the Standard, the description for 

   int MPI_T_pvar_get_info(..., int *readonly, int *continuous, int *atomic)
says:
  Upon return, the argument readonly is set to zero if the variable can be written or reset by the user. It is set to one if the variable can only be read. 

  (Same thing happens to continuous and atomic.)

The description mandates an implementation must return 1 as TRUE, which does not follow C's convention. Other parts of MPI use true/false instead of 1/0 in description.  Section 2.6.3 make it clear that true means non-zero.