scilab-ann needs to recompile against scilab in repo

[Mark]

the scilab-ann package is incompatible with the main scilab:

```
Start ANN Toolbox 0.4.2.4
 Load macros
at line 22 of executed file /usr/lib/scilab-ann/etc/ANN_toolbox.start
at line 10 of executed file /usr/lib/scilab-ann/loader.sce
at line 1 of executed string

lib: Old binary lib detected. Please recompile it for Scilab 6.
```

The versions scilab (6.0) and scilab-ann (toolbox, v 4) mismatch.

$ LANG=C apt-cache policy scilab scilab-ann
scilab:
Installed: 6.0.1-7ubuntu1~18.04.1
Candidate: 6.0.1-7ubuntu1~18.04.1
Version table:
*** 6.0.1-7ubuntu1~18.04.1 500
500 mirror://mirrors.ubuntu.com/mirrors.txt bionic-updates/universe amd64 Packages
500 mirror://mirrors.ubuntu.com/mirrors.txt bionic-updates/universe i386 Packages
100 /var/lib/dpkg/status
6.0.1-7ubuntu1~18.04 500
500 mirror://mirrors.ubuntu.com/mirrors.txt bionic-security/universe amd64 Packages
500 mirror://mirrors.ubuntu.com/mirrors.txt bionic-security/universe i386 Packages
6.0.1-1ubuntu1 500
500 mirror://mirrors.ubuntu.com/mirrors.txt bionic/universe amd64 Packages
500 mirror://mirrors.ubuntu.com/mirrors.txt bionic/universe i386 Packages
scilab-ann:
Installed: 0.4.2.4-1
Candidate: 0.4.2.4-1
Version table:
*** 0.4.2.4-1 500
500 mirror://mirrors.ubuntu.com/mirrors.txt bionic/universe amd64 Packages
500 mirror://mirrors.ubuntu.com/mirrors.txt bionic/universe i386 Packages
100 /var/lib/dpkg/status