fix(build): compile boringssl C++ with g++ to resolve libstdc++ headers on musl; verified locally

Author: dvershinin

Dockerfile

@@ -8,7 +8,7 @@ RUN apk add --no-cache build-base git autoconf libpsl-dev libtool cmake go curl
 
 # Prefer clang toolchain for BoringSSL/quiche on all arches (including arm64)
 ENV CC=clang
-ENV CXX=clang++
+ENV CXX=g++
 
 COPY _dl/quiche.tar.gz /opt/quiche.tar.gz
 COPY _dl/curl.tar.gz /opt/curl.tar.gz