Add basic support for tvOS

[sbeca]

What does this PR do?

This PR adds basic support for targeting tvOS.

For reference, when you're writing code that targets both iOS and tvOS, there are a bunch of small differences you have to worry about, but from an Xcode configuration point of view, there are only a few differences between iOS and tvOS:

1. Need to target the appletvos SDK instead of the iphoneos SDK.
2. Need to use TVOS_DEPLOYMENT_TARGET to set the min OS version supported, instead of IPHONEOS_DEPLOYMENT_TARGET.
3. There is no tvOS equivalent to iosfamily, so that can just be ignored.

So the amount of changes required for Premake to support tvOS is relatively small, with a large percent of the additions in this PR being duplications of iOS unit tests with minor changes.

How does this PR change Premake's behavior?

A new target OS has been added.

Anything else we should know?

To show how similar iOS and tvOS are from a builds perspective, I was literally using this small snippet of bash code to smash the small amount of changes needed from an iOS build, and that got things building successfully for tvOS:

function smash_tvos_changes {
  # HACK: Premake doesn't currently support tvOS as a separate target OS, so we passed iOS to Premake earlier in this script, and now we're going to smash
  # a small amount of changes needed to change the Xcode project from targeting iOS to targeting tvOS, that can't be overridden with Premake config

  # Need to convert lines like:
  #   "CODE_SIGN_IDENTITY[sdk=iphoneos*]" = "Apple Development";
  #   SDKROOT = iphoneos;
  # to:
  #   "CODE_SIGN_IDENTITY[sdk=appletvos*]" = "Apple Development";
  #   SDKROOT = appletvos;
  sed -i '' 's/iphoneos/appletvos/' "$1"

  # Need to convert lines like:
  #   IPHONEOS_DEPLOYMENT_TARGET = 12.0;
  # to:
  #   TVOS_DEPLOYMENT_TARGET = 12.0;
  sed -i '' 's/IPHONEOS_DEPLOYMENT_TARGET/TVOS_DEPLOYMENT_TARGET/' "$1"
}

if [ "${TARGET_OS}" == "tvos" ]; then
  smash_tvos_changes "${SOURCE_DIR}/Generated/${PROJECT}.xcodeproj/project.pbxproj"
fi

I would love to get tvOS support upstreamed, so I don't need to do ugly hacks like this anymore haha

Did you check all the boxes?

• Focus on a single fix or feature; remove any unrelated formatting or code changes
• Add unit tests showing fix or feature works; all tests pass
• Mention any related issues (put closes #XXXX in comment to auto-close issue when PR is merged)
• Follow our coding conventions
• Minimize the number of commits
• Align documentation to your changes

You can now support Premake on our OpenCollective. Your contributions help us spend more time responding to requests like these!

[sbeca]

This is something I'm not quite sure on, what tags should tvOS have?

An Apple TV isn't a desktop device and it isn't a mobile device, but an Apple TV's internals are very similar to an iPhone, and iOS and tvOS share a lot of common history and functionality. So because of the familiarity to iOS I tagged it as mobile but I'm open to other suggestions

[sbeca]

This is a pre-existing issue, and not directly relevant to this PR so I haven't touched it, but I want to say that mentioning watchOS in this sentence is not super correct in my opinion.

First, Premake doesn't directly support watchOS, so mentioning it at all without also saying Premake doesn't support it seems wrong.

Second, watchOS doesn't even use this compiler flag as Clang has a separate -mwatchos-version-min compiler flag just for watchOS, unless Clang has some weird internal logic where it falls back to using the iOS flag when the watchOS flag isn't specified

[Jarod42]

Possibly

Suggested change

	local name = iif(cfg.system == p.MACOSX, "macosx", "iphoneos")
	local name = "macosx"
	if cfg.system == p.IOS then
	name = "iphoneos"
	elseif cfg.system == p.TVOS then
	name = "appletvos"
	end
	local names = {
	p.MACOSX = "macosx",
	p.IOS = "iphoneos",
	p.TVOS = "appletvos"
	}
	local name = names[cfg.system]