CI: Include stdlib build for Wasm in the Linux buildbot

This makes the WebAssembly stdlib build mandatory as part of PR testing.

Author: kateinoigakukun

utils/build-presets.ini

@@ -836,6 +836,9 @@ build-swift-static-stdlib
 build-swift-static-sdk-overlay
 build-swift-stdlib-unittest-extra
 
+wasmkit
+build-wasm-stdlib
+
 # Executes the lit tests for the installable package that is created
 # Assumes the swift-integration-tests repo is checked out