utils: update experimental SDK builds

Adjust the build of the experimental SDK to build libdispatch
statically.

Author: compnerd

utils/build.ps1

@@ -710,6 +710,7 @@ enum Project {
   ExperimentalOverlay
   ExperimentalStringProcessing
   ExperimentalSynchronization
+  ExperimentalDispatch
   StaticFoundation
 }
 
@@ -2716,6 +2717,29 @@ function Build-ExperimentalSDK([Hashtable] $Platform) {
   # TODO(compnerd) we currently build the experimental SDK with just the static
   # variant. We should aim to build both dynamic and static variants.
   Invoke-BuildStep Build-ExperimentalRuntime $Platform -Static
+
+  Invoke-IsolatingEnvVars {
+    $env:Path = "$(Get-CMarkBinaryCache $Platform)\src;$(Get-PinnedToolchainRuntime);${env:Path}"
+    Build-CMakeProject `
+      -Src $SourceCache\swift-corelibs-libdispatch `
+      -Bin (Get-ProjectBinaryCache $Platform ExperimentalDispatch) `
+      -InstallTo "$(Get-SwiftSDK $Platform.OS -Identifier "$($Platform.OS)Experimental")\usr" `
+      -Platform $Platform `
+      -UseBuiltCompilers C,CXX,Swift `
+      -SwiftSDK (Get-SwiftSDK $Platform.OS -Identifier "$($Platform.OS)Experimental") `
+      -Defines @{
+        BUILD_SHARED_LIBS = "NO";
+        CMAKE_FIND_PACKAGE_PREFER_CONFIG = "YES";
+        CMAKE_Swift_COMPILER_TARGET = (Get-ModuleTriple $Platform);
+        CMAKE_Swift_COMPILER_WORKS = "YES";
+        CMAKE_Swift_FLAGS = @("-static-stdlib", "-Xfrontend", "-use-static-resource-dir");
+        CMAKE_STATIC_LIBRARY_PREFIX_Swift = "lib";
+        CMAKE_SYSTEM_NAME = $Platform.OS.ToString();
+
+        ENABLE_SWIFT = "YES";
+      }
+  }
+
   Invoke-BuildStep Build-Foundation $Platform -Static
 }