builder: Add libatomic1 package

Signed-off-by: Tam Mach <tam.mach@cilium.io>

Author: sayboras

Dockerfile.builder

@@ -23,7 +23,7 @@ RUN apt-get update && \
       libc6-dev \
       # Envoy Build dependencies
       autoconf automake cmake coreutils curl git libtool make ninja-build patch patchelf \
-	python3 python-is-python3 unzip virtualenv wget zip \
+	  python3 python-is-python3 unzip virtualenv wget zip libatomic1 \
       # Cilium-envoy build dependencies
       software-properties-common && \
     wget -qO- https://apt.llvm.org/llvm-snapshot.gpg.key | tee /etc/apt/trusted.gpg.d/apt.llvm.org.asc && \