Auto merge of #140064 - EnzymeAD:enable-autodiff-in-ci, r=<try>

[DO NOT MERGE] start building enzyme on x86_64-gnu-llvm-{19|20} builders

My goal is to put this in CI on April 26, to have a week to land some of the outstanding PRs:
#139700
#139308
#139557
#140030
#140049
The autodiff flags PR should land first, but otherwise they don't overlap and are mostly ready, so it shouldn't be too hard to land them. In the meantime, I'll experiment here with some builders.

r? `@oli-obk`

Tracking:

- #124509

try-job: dist-x86_64-linux

Author: bors

src/ci/docker/host-x86_64/dist-x86_64-linux/Dockerfile

@@ -90,6 +90,8 @@ ENV RUST_CONFIGURE_ARGS \
       --set target.x86_64-unknown-linux-gnu.ranlib=/rustroot/bin/llvm-ranlib \
       --set llvm.thin-lto=true \
       --set llvm.ninja=false \
+      --set llvm.plugins=true \
+      --set llvm.enzyme=true \
       --set llvm.libzstd=true \
       --set rust.jemalloc \
       --set rust.use-lld=true \

src/ci/docker/host-x86_64/x86_64-gnu-llvm-19/Dockerfile

@@ -52,6 +52,7 @@ ENV RUST_CONFIGURE_ARGS \
       --build=x86_64-unknown-linux-gnu \
       --llvm-root=/usr/lib/llvm-19 \
       --enable-llvm-link-shared \
+      --enable-llvm-enzyme \
       --set rust.randomize-layout=true \
       --set rust.thin-lto-import-instr-limit=10
 

src/ci/docker/host-x86_64/x86_64-gnu-llvm-20/Dockerfile

@@ -52,6 +52,7 @@ ENV RUST_CONFIGURE_ARGS \
       --build=x86_64-unknown-linux-gnu \
       --llvm-root=/usr/lib/llvm-20 \
       --enable-llvm-link-shared \
+      --enable-llvm-enzyme \
       --set rust.randomize-layout=true \
       --set rust.thin-lto-import-instr-limit=10
 

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

@@ -30,4 +30,6 @@ ENV RUST_CONFIGURE_ARGS \
  --enable-profiler \
  --enable-compiler-docs \
  --set llvm.libzstd=true
+ --set llvm.plugins=true \
+ --set llvm.enzyme=true \
 ENV SCRIPT python3 ../x.py --stage 2 test