s3:tests: Add smbspool test for CUPS-like "sanitized" Device URI in argv[0]

s3:tests: Add smbspool test for CUPS-like "sanitized" Device URI in argv[0]

Before calling a backend like smbspool, CUPS will set argv[0] to the
"sanitized" Device URI (the Device URI with username/password
information removed).  These changes are intended to catch problems
with smbspool that may be created by this behavior (like
https://bugzilla.samba.org/show_bug.cgi?id=14128).

source3/script/tests/smbspool_argv_wrapper.c: added to emulate
CUPS-like behavior by setting argv[0] to the device URI before
exec()ing smbspool.

source3/script/tests/test_smbspool.sh: updated to use
smbspool_argv_wrapper to test the CUPS-like behavior described above.

Signed-off-by: Bryan Mason <bmason@redhat.com>
Reviewed-by: Andreas Schneider <asn@samba.org>
Reviewed-by: Alexander Bokovoy <ab@samba.org>
Autobuild-User(master): Andreas Schneider <asn@cryptomilk.org>
Autobuild-Date(master): Wed Oct 16 10:55:04 UTC 2019 on sn-devel-184