[CI] Fix out-of-tree build by installing mlir-tools

LLVMExports.cmake from already installed packages references files
from the mlir-tools package.

Author: svenvh

.github/workflows/check-code-style.yml

@@ -63,7 +63,8 @@ jobs:
         sudo apt-get update
         sudo apt-get install -yqq \
             clang-format-${{ env.LLVM_VERSION }} clang-tidy-${{ env.LLVM_VERSION }} \
-            llvm-${{ env.LLVM_VERSION }}-dev libomp-${{ env.LLVM_VERSION }}-dev
+            llvm-${{ env.LLVM_VERSION }}-dev libomp-${{ env.LLVM_VERSION }}-dev \
+            mlir-${{ env.LLVM_VERSION }}-tools \
 
     - name: Generate compile command database
       if: ${{ steps.gather-list-of-changes.outputs.HAS_CHANGES }}

.github/workflows/check-out-of-tree-build.yml

@@ -52,6 +52,7 @@ jobs:
             llvm-${{ env.LLVM_VERSION }}-dev \
             libomp-${{ env.LLVM_VERSION }}-dev \
             llvm-${{ env.LLVM_VERSION }}-tools \
+            mlir-${{ env.LLVM_VERSION }}-tools \
             spirv-tools
           # Linux systems in GitHub Actions already have older versions of clang
           # pre-installed. Make sure to override these with the relevant version.