Fixes minor issues in various virtual file drivers

- HDFS VFD files now ignored in the Autotools when the HDFS VFD is not
  being built.
- All VFD init code uses idiomatic H5I_INVALID_HID instead of -1
  or FAIL.
- The HDFS VFD now includes H5FDdrvr_module.h in the right place.
- The HDFS tests in test/hdfs.c no longer pass NULL to VERIFY macros, which
  raised warnings.
- Minor tweaks to fix const, unused variables, etc. warnings in
  several VFDs.

1 files changed, 0 insertions, 2 deletions

diff --git a/test/vfd.c b/test/vfd.c
index ae4921c..4ba0422 100644
--- a/test/vfd.c
+++ b/test/vfd.c
@@ -2168,8 +2168,6 @@ test_ros3(void)
     hid_t            driver_id    = -1;     /* ID for this VFD              */
     unsigned long    driver_flags = 0;      /* VFD feature flags            */
     char             filename[1024];        /* filename                     */
-    void *           os_file_handle = NULL; /* OS file handle               */
-    hsize_t          file_size;             /* file size                    */
     H5FD_ros3_fapl_t test_ros3_fa;
     H5FD_ros3_fapl_t ros3_fa_0 = {
         /* version      = */ H5FD_CURR_ROS3_FAPL_T_VERSION,