Fix PACKAGE_VERSION output in sdl2_image-config-version.cmake

[bcarmo-caio]

Currently, when executing ./autogen.sh and ./configure we get the following sdl2_image-config-version.cmake

...
set(PACKAGE_VERSION "@MAJOR_VERSION_MACRO@.@MINOR_VERSION_MACRO@.@MICRO_VERSION_MACRO@")
...

This PR fixes this issue using the correct variable names and producing a proper file like

...
set(PACKAGE_VERSION "2.6.3")
...

[sezero]

I tried to change target branch from release-2.6.x to SDL2 but that
doesn't work. If we do merge this to the release branch, we can cherry pick
to SDL2 branch, though.

P.S.: Curious failure in CI macos runs: any ideas @madebr ?

==> Fetching sdl2
==> Downloading https://raw.githubusercontent.com/Homebrew/homebrew-core/79823708f871f744e3aa0e6630b6f837c3d2981f/Formula/s/sdl2.rb
==> Cloning https://github.com/libsdl-org/SDL.git
Cloning into '/Users/runner/Library/Caches/Homebrew/sdl2--git'...
==> Checking out branch main
Already on 'main'
Your branch is up to date with 'origin/main'.
Error: An exception occurred within a child process:
  Errno::ENOENT: No such file or directory @ rb_sysopen - sdl2.pc.in
Error: Process completed with exit code 1.

[madebr]

P.S.: Curious failure in CI macos runs: any ideas @madebr ?

Homebrew/homebrew-core#149190

We don't need the --HEAD anymore.
It was introduced to work around a bug in a early CMake configuration file.

[sezero]

Should we merge this as is to release branch and cherry-pick to SDL2 later?

[madebr]

Should we merge this as is to release branch and cherry-pick to SDL2 later?

That's the normal procedure, but imho the order does not matter much since the change looks trivial (I've not yet tested it).

[madebr]

Cherry-picked to SDL2 in 70527e1

[bcarmo-caio]

Hi there. Thank you for merging the PR so fast and sorry for mistaking the branch names.

I would like to open one more PR. Should I set the base to SDL2 instead of release-2.6.x this time?

Regards

[sezero]

I would like to open one more PR. Should I set the base to SDL2 instead of release-2.6.x this time?

Yes: SDL2-related changes should be against SDL2 branch. If found necessary, they will be applied back to the release branch.

[madebr]

In order of preference, depending on what you want to propose and whether it's still present in SDL3:

1. main (SDL3)
2. SDL2
3. release-2.6.x

[bcarmo-caio]

Great. Thank you for letting me know