libgerbv.pc in gerbv package is missing version number

[Eyal Soha]

The gerbv package which installs the file libgerbv.pc is missing a version number. This issue does not occur on MX Linux nor does it occur when installing from sources.

The procedure to get the package and examine the libgerbv.pc file is:

```bash
cd ~/tmp
mkdir gerbv2
cd gerbv2
wget 'http://mirrors.kernel.org/ubuntu/pool/universe/g/gerbv/gerbv_2.8.2-1_amd64.deb'
ar x gerbv_2.8.2-1_amd64.deb
tar xvf data.tar.*
cat `find . -name libgerbv.pc`
```

The bug report on gerbv is: https://github.com/gerbv/gerbv/issues/130

The problem was discovered while compiling pcb2gcode and reported here: https://github.com/pcb2gcode/pcb2gcode/issues/626

I was told to file a bug: https://answers.launchpad.net/ubuntu/+source/gerbv/+question/702967

I am not using Ubuntu but my users are and some of them have complained.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.