fix ci build for static sdk

Author: sebsto

.github/workflows/pull_request.yml

@@ -29,6 +29,13 @@ jobs:
       swift_flags: "--explicit-target-dependency-import-check error"
       swift_nightly_flags: "--explicit-target-dependency-import-check error"
       enable_linux_static_sdk_build: true
+      # The static Linux SDK statically links against musl. AWSLambdaPluginHelper pulls in
+      # SotoCore, which transitively brings two different vendored BoringSSL forks
+      # (swift-crypto's CCryptoBoringSSL and swift-nio-ssl's CNIOBoringSSL). Static linking
+      # surfaces their duplicate libc++abi symbols (set_new_handler, __cxa_*, ...) and the link
+      # fails. The helper is a host-side build tool that never runs inside Lambda, so it does not
+      # need the static SDK. Restrict the static build to the deployable runtime product.
+      linux_static_sdk_build_command: "swift build --product AWSLambdaRuntime"
 
   integration-tests:
     name: Integration Tests