GHA: generate SDKSettings.json

This was added upstream, follow suite and generate this here as this is
needed for packaging.

Author: compnerd

.github/workflows/swift-toolchain.yml

@@ -2496,6 +2496,24 @@ jobs:
               # runtime.
               plistlib.dump({ 'DefaultProperties': { 'DEFAULT_USE_RUNTIME': 'MD' } }, plist)
 
+      - run: |
+          $SDKSettings = @{
+            CanonicalName = "${{ matrix.triple }}"
+            DisplayName = "${{ matrix.os }}"
+            IsBaseSDK = "NO"
+            Version = "${{ inputs.swift_version }}"
+            VersionMap = @{}
+            DefaultProperties = @{
+              PLATFORM_NAME = "${{ matrix.os }}"
+              DEFAULT_COMPILER = [string]::Format(".org.compnerd.dt.toolchain.{0}.{1}-asserts", (Get-Date -Format "yyyymmdd"), ((Get-Date).Hour % 6))
+            }
+          }
+          if ("${{ matrix.os }}" -eq "Windows") {
+            $SDKSettings.DefaultProperties.DEFAULT_USE_RUNTIME = "MD"
+          }
+          New-Item -ItemType Directory -Path "${{ github.workspace }}/BuildRoot/Library/Developer/Platforms/${{ matrix.os }}.platform/Developer/SDKs/${{ matrix.os }}.sdk" -Force | Out-Null
+          $SDKSettings | ConvertTo-JSON | Out-File -FilePath "${{ github.workspace }}/BuildRoot/Library/Developer/Platforms/${{ matrix.os }}.platform/Developer/SDKs/${{ matrix.os }}.sdk/SDKSettings.json"
+
       - uses: actions/upload-artifact@v4
         if: matrix.os != 'Android' || inputs.build_android
         with: