Bug#661561: lintian: Please improve source-contains-waf-binary tag

[Dmitrijs Ledkovs <dmitrij.ledkov@ubuntu.com>]

Package: lintian
Version: 2.5.5
Severity: normal

The waf tag implemented in #654523 generates false positives, when
package has implemented changes as described in
http://wiki.debian.org/UnpackWaf

source-contains-waf-binary tag will still be triggered, since executable
python file called 'waf' is still present after unpacking.

Here are some possible additional conditions to add, which will
remove false positives for the case when UnpackWaf was performed:

- AND waflib/ does not exist
- AND waf is < 5kB
- AND waf does not contain regexp ^#==>$
- AND waf is plain text / doesn't contain funny binary data

Please let me know what you prefer best and I can implement a patch.

Regards,

Dmitrijs.