Correctly set codegen backends for GCC jobs

Author: Kobzol

src/ci/docker/host-x86_64/x86_64-gnu-gcc-core-tests/Dockerfile

@@ -1,5 +1,5 @@
-# This Dockerfile builds sysroot crates with the GCC backend and then run libcore tests
-# with it.
+# This Dockerfile builds sysroot crates with the GCC backend and then runs
+# libcore tests with the GCC backend.
 
 FROM ubuntu:22.04
 
@@ -34,14 +34,14 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+ENV CODEGEN_BACKENDS="gcc"
 ENV NO_DEBUG_ASSERTIONS="1"
 ENV RUSTFLAGS="-Cpanic=abort -Zpanic-abort-tests"
 ENV RUST_CONFIGURE_ARGS="--build=x86_64-unknown-linux-gnu \
  --enable-sanitizers \
  --enable-profiler \
  --enable-compiler-docs \
- --set llvm.libzstd=true \
- --set rust.codegen-backends=[\\\"gcc\\\"]"
+ --set llvm.libzstd=true"
 ENV SCRIPT="python3 ../x.py \
   --stage 1 \
   test library/coretests"

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

@@ -1,5 +1,5 @@
-# This Dockerfile builds sysroot with the LLVM backendsthen run tests with the
-# GCC backend.
+# This Dockerfile builds sysroot with the LLVM backend and then runs tests
+# with the GCC backend.
 
 FROM ubuntu:22.04
 
@@ -34,13 +34,13 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh
 
+ENV CODEGEN_BACKENDS="llvm,gcc"
 ENV NO_DEBUG_ASSERTIONS="1"
 ENV RUST_CONFIGURE_ARGS="--build=x86_64-unknown-linux-gnu \
  --enable-sanitizers \
  --enable-profiler \
  --enable-compiler-docs \
- --set llvm.libzstd=true \
- --set rust.codegen-backends=[\\\"llvm\\\",\\\"gcc\\\"]"
+ --set llvm.libzstd=true"
 ENV SCRIPT="python3 ../x.py \
   --stage 2 \
   test tests \
@@ -52,5 +52,4 @@ ENV SCRIPT="python3 ../x.py \
   --skip tests/rustdoc-js \
   --skip tests/rustdoc-js-std \
   --skip tests/rustdoc-json \
-  --skip tests/rustdoc-ui \
-  --set rust.codegen-backends=[\\\"llvm\\\",\\\"gcc\\\"]"
+  --skip tests/rustdoc-ui"