build: Rename wasi-threads to wasip1-threads

The WASI community is transitioning to a new naming for the "preview"
version in the target triple: wasm32-wasi -> wasm32-wasip1.
At this moment, we keep the old triple wasm32-wasi because it's already
widely used, but we should start using the new triple threaded target.

LLVM checks only if the OS field *starts* with "wasi", so "wasip1" is
still considered a valid `isOSWASI()` target.

See: WebAssembly/wasi-libc#478

cmake/modules/SwiftConfigureSDK.cmake

@@ -423,7 +423,7 @@ macro(configure_sdk_unix name architectures)
         endif()
         set(SWIFT_SDK_WASI_ARCH_wasm32_PATH "${SWIFT_WASI_SYSROOT_PATH}")
         if(SWIFT_ENABLE_WASI_THREADS)
-          set(SWIFT_SDK_WASI_ARCH_wasm32_TRIPLE "wasm32-unknown-wasi-threads")
+          set(SWIFT_SDK_WASI_ARCH_wasm32_TRIPLE "wasm32-unknown-wasip1-threads")
         else()
           set(SWIFT_SDK_WASI_ARCH_wasm32_TRIPLE "wasm32-unknown-wasi")
         endif()

utils/swift_build_support/swift_build_support/products/wasisysroot.py

@@ -148,7 +148,7 @@ def _build(self, host_target, enable_wasi_threads=False):
 
         libdir_suffix = '/wasm32-wasi'
         if enable_wasi_threads:
-            libdir_suffix = '/wasm32-wasi-threads'
+            libdir_suffix = '/wasm32-wasip1-threads'
         self.cmake_options.define('LIBCXX_LIBDIR_SUFFIX:STRING', libdir_suffix)
         self.cmake_options.define('LIBCXXABI_LIBDIR_SUFFIX:STRING', libdir_suffix)
         self.cmake_options.define('CMAKE_STAGING_PREFIX:PATH', '/')
@@ -188,7 +188,7 @@ def _build(self, host_target, enable_wasi_threads=False):
         self.cmake_options.define('CMAKE_C_FLAGS:STRING', ' '.join(c_flags))
         self.cmake_options.define('CMAKE_CXX_FLAGS:STRING', ' '.join(cxx_flags))
 
-        target_triple = 'wasm32-wasi-threads' if enable_wasi_threads else 'wasm32-wasi'
+        target_triple = 'wasm32-wasip1-threads' if enable_wasi_threads else 'wasm32-wasi'
         self.cmake_options.define('CMAKE_C_COMPILER_TARGET:STRING', target_triple)
         self.cmake_options.define('CMAKE_CXX_COMPILER_TARGET:STRING', target_triple)