[Cin] Patch HDR for Color3way

[Andrea paz]

>From this forum thread:

https://www.cinelerra-gg.org/forum/help-video/problem-with-colour3way/

After the patch to make Color3way work in float, even with values
above the range (0 - 1.0f), this problem occurs:

"If I move the Shadows Value slider to the left, by the time it
reaches 0.006 the image is almost totally black, which makes it
totally useless."

and:

"I confirm the problem. The color wheel also behaves the same way,
while the saturation slider works normally. Midtone and Highlight work
normally."

The applicated HDR patches can be seen here:

https://git.cinelerra-gg.org/git/?p=goodguy/cinelerra.git;a=commitdiff;h=3cdcd29150341dd26a8c61772f8473ab20a85fdd

I've tried a few builds/tests. The patches for Overlays and for
Histogram plugin seem to work normally. Only the patch for Color3way
causes a problem. This problem occurs only for shadows, which is
strange because the patch only alters the white boundary and leaves
the black boundary unchanged. I tried to read the plugin code but I am
not able to understand the problem. Does anyone understand anything
about it?

For now you could exclude the Color3way patch but put the other two back in.

PS: Using the overlays in the patchbay seems to me that the PorterDuff
do not work. This does not depend on the patch because I have the same
behavior even with the old appimages without the patch...