Merging in latest from upstream (HDFFV/hdf5:refs/heads/develop)

* commit 'b55a584fd5b3aac6f2514fba41a6182030b497ae':
  In portable shell scripts (using #!/bin/sh) we have to use single square brackets, [ ], instead of the bash-ism double square brackets, [[ ]].
  Make this script work on hosts where PERL is not installed at /usr/bin/perl.

bin/warnhist

@@ -1,5 +1,6 @@
-#!/usr/bin/perl -w
+#!/usr/bin/env perl
 require 5.003;
+use warnings;
 
 #
 # Copyright by The HDF Group.

hl/tools/h5watch/testh5watch.sh.in

@@ -18,7 +18,7 @@
 # supports SWMR.
 ./swmr_check_compat_vfd
 rc=$?
-if [[ $rc != 0 ]] ; then
+if [ $rc != 0 ] ; then
     echo
     echo "The VFD specified by the HDF5_DRIVER environment variable"
     echo "does not support SWMR."

tools/test/h5dump/testh5dump.sh.in

@@ -923,7 +923,7 @@ GREPTEST()
       cd $TESTDIR
       $ENVCMD $RUNSERIAL $DUMPER_BIN -p "$@"
     ) >$actual 2>$actual_err
-    if [[ "$txttype" = "ERRTXT" ]]; then
+    if [ "$txttype" = "ERRTXT" ]; then
         $GREP "$expectdata" $actual_err > /dev/null
     else
         $GREP "$expectdata" $actual > /dev/null