[tools] Fix computing the product version for Mac Catalyst.

[rolfbjarne]

This fixes a problem with the version number in error messages when only Mac Catalyst is enabled in the build:

warning MT0079: The recommended Xcode version for Microsoft.MacCatalyst @IOS_NUGET_VERSION@ is Xcode 16.2 or later.

[rolfbjarne]

/azp run xamarin-macios-pr,xamarin-macios-apidiff

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[rolfbjarne]

/azp run xamarin-macios-pr-apidiff

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[vs-mobiletools-engineering-service2]

✅ [CI Build] Build passed (Build packages) ✅

Pipeline on Agent
Hash: c2cab4665ec0bbd59ce12777fc36eb0e3d610323 [PR build]

[vs-mobiletools-engineering-service2]

✅ [CI Build] Build passed (Detect API changes) ✅

Pipeline on Agent
Hash: c2cab4665ec0bbd59ce12777fc36eb0e3d610323 [PR build]

[vs-mobiletools-engineering-service2]

💻 [CI Build] Windows Integration Tests passed 💻

✅ All Windows Integration Tests passed.

Pipeline on Agent
Hash: c2cab4665ec0bbd59ce12777fc36eb0e3d610323 [PR build]

[vs-mobiletools-engineering-service2]

✅ API diff for current PR / commit

.NET (No breaking changes)

• iOS: vsdrops gist (No breaking changes)
• tvOS: vsdrops gist (No breaking changes)
• MacCatalyst: vsdrops gist (No breaking changes)
• macOS: vsdrops gist (No breaking changes)

✅ API diff vs stable

.NET (No breaking changes)

• iOS: vsdrops gist (No breaking changes)
• tvOS: vsdrops gist (No breaking changes)
• MacCatalyst: vsdrops gist (No breaking changes)
• macOS: vsdrops gist (No breaking changes)

ℹ️ Generator diff

Generator Diff: vsdrops (html) vsdrops (raw diff) gist (raw diff) - Please review changes)

Pipeline on Agent
Hash: c2cab4665ec0bbd59ce12777fc36eb0e3d610323 [PR build]

[vs-mobiletools-engineering-service2]

✅ [CI Build] Build passed (Build macOS tests) ✅

Pipeline on Agent
Hash: c2cab4665ec0bbd59ce12777fc36eb0e3d610323 [PR build]

[vs-mobiletools-engineering-service2]

💻 [CI Build] Tests on macOS M1 - Mac Monterey (12) passed 💻

✅ All tests on macOS M1 - Mac Monterey (12) passed.

Pipeline on Agent
Hash: c2cab4665ec0bbd59ce12777fc36eb0e3d610323 [PR build]

[vs-mobiletools-engineering-service2]

💻 [CI Build] Tests on macOS X64 - Mac Sonoma (14) passed 💻

✅ All tests on macOS X64 - Mac Sonoma (14) passed.

Pipeline on Agent
Hash: c2cab4665ec0bbd59ce12777fc36eb0e3d610323 [PR build]

[vs-mobiletools-engineering-service2]

💻 [CI Build] Tests on macOS arm64 - Mac Sequoia (15) passed 💻

✅ All tests on macOS arm64 - Mac Sequoia (15) passed.

Pipeline on Agent
Hash: c2cab4665ec0bbd59ce12777fc36eb0e3d610323 [PR build]

[vs-mobiletools-engineering-service2]

💻 [CI Build] Tests on macOS M1 - Mac Ventura (13) passed 💻

✅ All tests on macOS M1 - Mac Ventura (13) passed.

Pipeline on Agent
Hash: c2cab4665ec0bbd59ce12777fc36eb0e3d610323 [PR build]

[vs-mobiletools-engineering-service2]

🔥 [CI Build] Test results 🔥

Test results

❌ Tests failed on VSTS: test results

0 tests crashed, 1 tests failed, 110 tests passed.

Failures

❌ generator tests [attempt 3]

1 tests failed, 4 tests passed.

• Roslyn Generator tests/.NET: Failed (Execution failed with exit code 1)

Html Report (VSDrops) Download

Successes

✅ cecil: All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (iOS): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (MacCatalyst): All 1 tests passed. [attempt 3] Html Report (VSDrops) Download
✅ dotnettests (macOS): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (Multiple platforms): All 1 tests passed. Html Report (VSDrops) Download
✅ dotnettests (tvOS): All 1 tests passed. Html Report (VSDrops) Download
✅ framework: All 2 tests passed. Html Report (VSDrops) Download
✅ fsharp: All 4 tests passed. Html Report (VSDrops) Download
✅ interdependent-binding-projects: All 4 tests passed. Html Report (VSDrops) Download
✅ introspection: All 4 tests passed. Html Report (VSDrops) Download
✅ linker: All 40 tests passed. [attempt 2] Html Report (VSDrops) Download
✅ monotouch (iOS): All 10 tests passed. Html Report (VSDrops) Download
✅ monotouch (MacCatalyst): All 10 tests passed. Html Report (VSDrops) Download
✅ monotouch (macOS): All 9 tests passed. [attempt 2] Html Report (VSDrops) Download
✅ monotouch (tvOS): All 10 tests passed. Html Report (VSDrops) Download
✅ msbuild: All 2 tests passed. Html Report (VSDrops) Download
✅ xcframework: All 4 tests passed. Html Report (VSDrops) Download
✅ xtro: All 1 tests passed. Html Report (VSDrops) Download

Pipeline on Agent
Hash: c2cab4665ec0bbd59ce12777fc36eb0e3d610323 [PR build]

[rolfbjarne]

Test failure is unrelated (#21864).