buildtools/wafsamba: Avoid decode when using python2

To avoid problematic type checking for 'str' types which fail
when result from str.decode is used.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=13777

Signed-off-by: Noel Power <noel.power@suse.com>
24 jobs for bso#13777 in 229 minutes and 39 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #157343196
docker shared
build_ctdb

00:43:15

passed #157443018
private docker
build_nt4

00:37:47

passed #157343199
docker shared
build_others

00:13:32

passed #157343201
docker private
build_samba

03:43:09

passed #157343204
docker private
build_samba_ad_dc

01:13:38

passed #157343189
docker shared
build_samba_ad_dc_2

00:30:18

passed #157343191
docker shared
build_samba_ad_dc_2_py2

00:25:52

passed #157343190
docker shared
build_samba_ad_dc_backup

00:29:54

passed #157343205
docker private
build_samba_ad_dc_py2

00:17:54

passed #157343200
docker shared
build_samba_buildpy2_only

00:18:34

passed #157343197
docker shared
build_samba_ctdb

00:20:15

passed #157343203
docker private
build_samba_fileserver

00:18:29

passed #157343192
docker shared
build_samba_libs

00:31:14

passed #157343194
docker shared
build_samba_libs_py2

00:34:41

passed #157352610
shared docker
build_samba_none_env

00:46:51

passed #157343182
docker shared
build_samba_none_env_py2

00:32:58

passed #157343184
docker shared
build_samba_nopython

00:28:26

passed #157343188
docker shared
build_samba_o3

00:32:48

passed #157343202
docker private
build_samba_py2

01:09:56

passed #157343195
docker shared
build_samba_static

00:45:37

passed #157343185
docker shared
build_samba_systemkrb5

00:15:55

passed #157343187
docker shared
build_samba_xc

00:07:00

failed #157343206
docker private
build_nt4

00:36:24

failed #157343181
docker shared
build_samba_none_env

00:06:14