Fix compiler warnings.

* For some reason gcc 9.1 does not detect that status is never used
  uninitialized.

src/pio_cdf_int.c

@@ -50,7 +50,7 @@ cdiPio_nc__create(const char *path, int cmode,
                   size_t initialsz, size_t *chunksizehintp,
                   int *ncidp)
 {
-  int status, ioMode = commInqIOMode();
+  int status = NC_EINVAL, ioMode = commInqIOMode();
   if (ioMode != PIO_NONE)
     {
 #if CDI_PIO_TRY_PNETCDF
@@ -148,6 +148,7 @@ cdiPio_enable_nc_par_access(int ncid, int streamID)
   if ( statusInq != NC_NOERR )
     Error("%s", nc_strerror(statusInq));
   setVarParAccess = (modeNC & NC_PNETCDF);
+  (void)streamID;
 #else
   int cf_format, owner = cdiPioStream2Owner(streamID);
   int statusInq = nc_inq_format(ncid, &cf_format);