[client] opengl: initialize scale to 1.0

[jacobmcnamee]

Fixes SPICE cursor rendering unconditionally at (0, 0) prior to KVMFR frame format configuration (using OpenGL renderer).

Presently cursor coordinates are multiplied by scale = 0 in opengl_onMouseEvent until opengl_onFrameFormat.

I observe this problem with a Win 10 VM using QXL video by running looking-glass-client app:renderer=OpenGL .

Note that some video devices / configurations embed the cursor in the video stream rather than sending SPICE cursor messages:

• QXL apparently defaults to a hardware cursor which is forwarded via SPICE (thus the issue manifests)
• Virtio currently disables hardware cursor support unless overridden via the registry (thus no issue for now)
• VGA seems unaffected