Disable automatic dependencies in zfs-test package

All of the ZTS test scripts specify /bin/ksh as the interpreter.
Unfortunately, as of Fedora 27 only /usr/bin/ksh is provided by
the package manager.  Rather than change all the scripts to
accommodate the latest Fedora disable automatic dependencies
for the zfs-test package.  Functionally this will not cause
any problems since /bin is a symlink to /usr/bin.

Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #6868

rpm/generic/zfs.spec.in

@@ -178,10 +178,12 @@ Requires:       lsscsi
 Requires:       mdadm
 Requires:       bc
 Requires:       ksh
-Requires:	fio
-Requires:	acl
-Requires:	sudo
-Requires:	sysstat
+Requires:       fio
+Requires:       acl
+Requires:       sudo
+Requires:       sysstat
+Requires:       rng-tools
+AutoReqProv:    no
 
 %description test
 This package contains test infrastructure and support scripts for