Replace interface not exactly matching the implementation.

* Unfortunately, C array parameters cannot have the restrict attribute
  thus better document the array characteristic and let the compiler
  optimize with aliasing restrictions in place.

src/pio_util.h

@@ -112,7 +112,21 @@ void printArray(const char *, const char *, const void *, int, int, const char *
  */
 int cdiPioQueryVarDims(int varShape[3], int vlistID, int varID);
 
-void cdiPioDeco1D_CCP(size_t n, const size_t weightPfxSums[n], size_t nparts, size_t separators[nparts + 1]);
+/**
+ * Computes simple, balanced 1D decomposition of weighted elements e.
+ *
+ * @param                 n number of elements to balance
+ * @param[in] weightPfxSums points to array of the \a n+1 partial
+ *                          weight sums, where
+ *                          weightPfxSums[i]-weightPfxSums[i-1] =
+ *                          weight of \$e_{i-1}\$
+ * @param            nparts number of parts to generate for partition
+ * @param[out]   separators pointer to array of size nparts+1,
+ *                          initialized by this function such that
+ *                          part i consists of elements indexed as
+ *                          separators[i] to separators[i+1]-1
+ */
+void cdiPioDeco1D_CCP(size_t n, const size_t *restrict weightPfxSums, size_t nparts, size_t *restrict separators);
 
 static inline size_t
 cdiPioElemSizeInference(size_t varID, const int *conversion)