Bump minimum Apple OS versions

[akoeplinger]

As defined in the ".NET 9 - Supported OS versions" document: https://github.com/dotnet/core/blob/main/release-notes/9.0/supported-os.md

• macOS 12.0
• iOS/iOSSimulator 12.2
• tvOS/tvOSSimulator 12.2
• MacCatalyst 15.0 (== macOS 12.0)

Fixes #91736

[filipnavara]

Looks like pal_signverify.c will need to silence a couple of deprecation warnings in the DSA code (SecTransformSetAttribute / SecTransformExecute). We already have a pattern for it elsewhere in the code:

runtime/src/native/libs/System.Security.Cryptography.Native.Apple/pal_keychain_macos.c

Lines 19 to 22 in a3dc133

	#pragma clang diagnostic push
	#pragma clang diagnostic ignored "-Wdeprecated-declarations"
	OSStatus status = SecKeychainItemCopyKeychain(item, pKeychainOut);
	#pragma clang diagnostic pop

There's no replacement for these APIs for this specific security algorithm, so the only other alternative is to drop the support entirely which is out of scope for this PR.

[akoeplinger]

Thanks, will add the suppression.

We're also seeing this in the maccatalyst build:

src/native/libs/System.Security.Cryptography.Native.Apple/pal_ssl.c(466,34): error G61EDB71E: (NETCORE_ENGINEERING_TELEMETRY=Build) 'SecTrustGetCertificateAtIndex' is deprecated: first deprecated in macCatalyst 15.0

[filipnavara]

The SecTrustGetCertificateAtIndex deprecation would need a new code path to use SecTrustCopyCertificateChain. To make that efficient we would likely need to rewrite the managed -> native interface. I guess it makes sense to suppress the deprecation and file an issue for a follow up work. I guess either I, or perhaps @vcsjones, can take a crack at it.

[akoeplinger]

Thanks, pushed the suppression and filed #101349

I also got an error when building locally with Xcode 15 from the new linker about -bind_at_load being deprecated for macOS (looks like it checks the min OS target since we didn't hit this before) so I also added a check to not pass that flag for the new linker.

[vcsjones]

I guess either I, or perhaps @vcsjones, can take a crack at it.

There are a number of deprecation suppressions we can tackle with the iOS version bump. I already have a branch to start this, so I can include this.

[ivanpovazan]

LGTM
Just a small comment: I noticed that the table in https://github.com/dotnet/core/blob/main/release-notes/9.0/supported-os.md is not in sync with these changes e.g., MacCatalyst version is specified as 12.0+

[akoeplinger]

... is not in sync with these changes e.g., MacCatalyst version is specified as 12.0+

Yeah this was accidentally overwritten: dotnet/core#9279