Symlink libclang_rt.builtins.a for Embedded Swift for WASI

Embedded Swift looks up clang compiler-rt in a different path than non-embedded. These paths could be normalized in the future, but for now the easiest fix seems to be just to symlink this static library.

Author: MaxDesiatov

Sources/SwiftSDKGenerator/SwiftSDKRecipes/WebAssemblyRecipe.swift

@@ -181,7 +181,7 @@ package struct WebAssemblyRecipe: SwiftSDKRecipe {
       )
     }
 
-    let autolinkExtractPath = generator.pathsConfiguration.toolchainBinDirPath.appending(
+    let autolinkExtractPath = pathsConfiguration.toolchainBinDirPath.appending(
       "swift-autolink-extract"
     )
 
@@ -195,6 +195,17 @@ package struct WebAssemblyRecipe: SwiftSDKRecipe {
       try await generator.createSymlink(at: autolinkExtractPath, pointingTo: "swift")
     }
 
+    // Embedded Swift looks up clang compiler-rt in a different path.
+    let embeddedCompilerRTPath = pathsConfiguration.toolchainDirPath.appending(
+      "usr/lib/swift/clang/lib/wasm32-unknown-wasip1"
+    )
+
+    try await generator.createDirectoryIfNeeded(at: embeddedCompilerRTPath)
+    try await generator.createSymlink(
+      at: embeddedCompilerRTPath.appending("libclang_rt.builtins.a"),
+      pointingTo: "../../../../swift_static/clang/lib/wasi/libclang_rt.builtins-wasm32.a"
+    )
+
     // Copy the WASI sysroot into the SDK bundle.
     let sdkDirPath = pathsConfiguration.swiftSDKRootPath.appending("WASI.sdk")
     try await generator.rsyncContents(from: self.wasiSysroot, to: sdkDirPath)