This patch enables video support for qimgv. VIDEO_SUPPORT=OFF is still
the default for the version of qimgv we have. Looks like it will be
enabled by default in the future though.
continuation of #109595
pkgconfig was aliased in 2018, however, it remained in
all-packages.nix due to its wide usage. This cleans
up the remaining references to pkgs.pkgsconfig and
moves the entry to aliases.nix.
python3Packages.pkgconfig remained unchanged because
it's the canonical name of the upstream package
on pypi.
I actually went back and `strace`'d the binary when it complained about
being unable to load the library it uses for playing videos. Turns out,
it wasn't finding the library because it wasn't in any of its library
paths. I added the lib path to `LD_LIBRARY_PATH` so it can find the
library it uses to play videos, and now things are peachy.
There is a (seemingly innocuous) error that gets displayed from Exiv2
being unable to determine its image type. Since it's actually a video, I
think it's fine. Another issue that pops up in the output is missing
`libcuda.so.1`, but that doesn't seem to affect functionality, and using
`addOpenGLRunpath` on both the binary and libraries didn't silence it.
Also did a little formatting.
