Fix execution on Ubuntu 20.04

[Adrian Sieber]

$ stack run -- fix images/doc.jpg
Loaded file images/doc.jpg (1500,880)
with orientation Normal
Starting the app …
freeglut (perspec): illegal glutInit() reinitialization attempt

Used build steps:

https://github.com/feramhq/Perspec/blob/63d1d37a185f85400ed03c7d8527f4becd2b9d8b/.github/workflows/main.yml#L46-L76

• Write answer to https://softwarerecs.stackexchange.com/questions/11282/software-to-straighten-an-oblique-rectangle-due-to-picture-perspective-to-2d-r

[jaccokrijnen]

Trying to reproduce this problem. I get a slightly different error:

$ stack run -- fix ./images/doc.jpg 
Loaded file /home/jacco/projects/Perspec/images/doc.jpg (1500,880)
with a rotation of 0.0 degrees.
perspec: user error (unknown GLUT entry glutInit)

[jaccokrijnen]

After apt installing freeglut3 The error changed to the one in the original post:

freeglut (perspec): illegal glutInit() reinitialization attempt

[Adrian Sieber]

freeglut and libglfw must be installed.