Engine: ali3dogl iOS fix for SDL renderbuffer

[ericoporto]

• SDL iOS OpenGL view (SDL_uikitopenglview.m) generates its own framebuffer, use it instead of 0
• Ensure that iOS is initialized with a 0 depth size to avoid generated depth framebuffers
• Add missing GL_FRAMEBUFFER_COMPLETE_EXT definition

@edmundito is working on the iOS port I left unfinished. Most of the changes are in the iOS directory. I want to pick the ones that aren't in small bits to make it easier to review, as there isn't a lot of stuff.

[ivan-mogilko]

Coincidentally we've been talking about this with edmundito on ags discord, so I'm little aware about some details here.

In regards to PR though:

I want to pick the ones that aren't in small bits to make it easier to review, as there isn't a lot of stuff.

Would it not be more convenient to gather all of these fixes in a single PR and merge when it's ready?
That would make it easier to port elsewhere too if wanted for some reason.

There's no problem reviewing a larger PR at all, so long as changes are split between commits thematically.

[ericoporto]

ok, the diff of the PR will look huge because it starts by deleting everything in iOS directory and there's a lot of old things there - Xcode project that is completely useless, patches that aren't needed, headers for entire libraries and other things that don't make sense. Passed this, the other changes are quite contained.

[ivan-mogilko]

For information, I had to add a fix: 7a0680d

I guess this could cause render mistakes with "render in screen resolution" mode.

[ericoporto]

Interestingly this was in @edmundito original commit, but I couldn't find any difference when testing and decided to drop - I was trying to keep changes at the minimum and break commits in small parts at the time.