Add no-opt standard library builders

We already have builders which built standard library *test*s without
optimizations, but we previously did not have builders which built the standard
library itself without optimizations and then tested that.

This adds those builds for i686 and x86_64 linux.

src/ci/docker/host-x86_64/i686-gnu-nopt/Dockerfile

@@ -19,8 +19,13 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+RUN mkdir -p /config
+RUN echo "[rust]" > /config/nopt-std-config.toml
+RUN echo "optimize = false" >> /config/nopt-std-config.toml
+
 ENV RUST_CONFIGURE_ARGS --build=i686-unknown-linux-gnu --disable-optimize-tests
-ENV SCRIPT python3 ../x.py --stage 2 test
+ENV SCRIPT python3 ../x.py test --stage 0 --config /config/nopt-std-config.toml library/std \
+  && python3 ../x.py --stage 2 test
 
 # FIXME(#59637) takes too long on CI right now
 ENV NO_LLVM_ASSERTIONS=1 NO_DEBUG_ASSERTIONS=1

src/ci/docker/host-x86_64/x86_64-gnu-nopt/Dockerfile

@@ -18,7 +18,12 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+RUN mkdir -p /config
+RUN echo "[rust]" > /config/nopt-std-config.toml
+RUN echo "optimize = false" >> /config/nopt-std-config.toml
+
 ENV RUST_CONFIGURE_ARGS --build=x86_64-unknown-linux-gnu \
   --disable-optimize-tests \
   --set rust.test-compare-mode
-ENV SCRIPT python3 ../x.py --stage 2 test
+ENV SCRIPT python3 ../x.py test --stage 0 --config /config/nopt-std-config.toml library/std \
+  && python3 ../x.py --stage 2 test