Skip building cranelift for Fuchsia

Author: tmandry

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

@@ -52,6 +52,9 @@ RUN sh /scripts/sccache.sh
 ENV RUST_INSTALL_DIR /checkout/obj/install
 RUN mkdir -p $RUST_INSTALL_DIR/etc
 
+# Fuchsia only supports LLVM.
+ENV CODEGEN_BACKENDS llvm
+
 ENV RUST_CONFIGURE_ARGS \
   --prefix=$RUST_INSTALL_DIR \
   --sysconfdir=etc \

src/ci/run.sh

@@ -130,10 +130,10 @@ else
   # tests as it will fail them.
   if [[ "${ENABLE_GCC_CODEGEN}" == "1" ]]; then
     # Test the Cranelift and GCC backends in CI. Bootstrap knows which targets to run tests on.
-    RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set rust.codegen-backends=llvm,cranelift,gcc"
+    RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set rust.codegen-backends=${CODEGEN_BACKENDS:-llvm,cranelift,gcc}"
   else
     # Test the Cranelift backend in CI. Bootstrap knows which targets to run tests on.
-    RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set rust.codegen-backends=llvm,cranelift"
+    RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set rust.codegen-backends=${CODEGEN_BACKENDS:-llvm,cranelift}"
   fi
 
   # We enable this for non-dist builders, since those aren't trying to produce