ctdb-build: Tweak hacking of rpcgen output

csbuild doesn't like the hack where variable buf is initialised to
itself to avoid an unused variable warning.  buf is unused so remove
it instead.

Signed-off-by: Martin Schwenke <martin@meltin.net>
30 jobs for MartinSchwenke-ctdb-csbuild in 65 minutes and 49 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #242716017
docker shared
centos7-samba-o3

00:35:42

passed #242716005
docker shared
ctdb

00:38:36

passed #242716015
docker shared
debian9-samba-o3

00:34:33

passed #242716018
docker shared
fedora29-samba-o3

00:37:01

passed #242716019
docker shared
fedora30-samba-o3

00:36:18

passed #242716016
docker shared
opensuse150-samba-o3

00:40:53

passed #242715990
docker shared
others

00:14:07

passed #242715991
docker shared
samba

00:25:52

passed #242716010
docker samba-ci-private
samba-ad-dc-1

00:45:55

passed #242715998
docker shared
samba-ad-dc-2

01:05:26

passed #242715999
docker shared
samba-ad-dc-3

00:45:43

passed #242716000
docker shared
samba-ad-dc-4

00:57:47

passed #242716001
docker shared
samba-ad-dc-5

00:47:17

passed #242716002
docker shared
samba-ad-dc-6

00:38:49

passed #242716008
docker samba-ci-private
samba-ad-dc-backup

00:52:29

passed #242716007
docker shared
samba-ad-dc-ntvfs

00:46:00

passed #242715997
docker shared
samba-ad-member

00:27:52

passed #242716006
docker shared
samba-ctdb

00:22:47

passed #242716009
docker samba-ci-private
samba-fileserver

00:30:56

passed #242716003
docker shared
samba-libs

00:39:00

passed #242715992
docker shared
samba-none-env

00:56:57

passed #242715993
docker shared
samba-nopython

00:33:52

passed #242715994
docker shared
samba-nopython-py2

00:46:35

passed #242716011
docker samba-ci-private
samba-nt4

00:43:08

passed #242716012
docker samba-ci-private
samba-schemaupgrade

00:22:20

passed #242716004
docker shared
samba-static

00:51:44

passed #242715995
docker shared
samba-systemkrb5

00:20:22

passed #242715996
docker shared
samba-xc

00:05:59

passed #242716014
docker shared
ubuntu1604-samba-o3

00:34:38

passed #242716013
docker shared
ubuntu1804-samba-o3

00:33:43