Set LD_LIBRARY_PATH and LIBRARY_PATH only if needed in CI

Author: GuillaumeGomez

.github/workflows/gcc12.yml

@@ -52,6 +52,8 @@ jobs:
     - name: Set env
       run: |
         echo "workspace="$GITHUB_WORKSPACE >> $GITHUB_ENV
+        echo "LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/12" >> $GITHUB_ENV
+        echo "LD_LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/12" >> $GITHUB_ENV
 
     #- name: Cache rust repository
       ## We only clone the rust repository for rustc tests