FIX: Env testing, overwrite old compilers

env/sles15/aarch64/admin/testing/spack.yaml

@@ -30,5 +30,27 @@ spack:
             set:
               SLURM_MPI_TYPE: 'pmix'
               OMPI_MCA_mtl_ofi_disable_hmem: 'true'
+  packages:
+    # overwrite any existing compiler
+    'cce:':
+      buildable: true
+    'gcc:':
+      buildable: true
+    'nvhpc:':
+      buildable: true
   specs: []
   view: false
+  compilers:
+  - compiler:
+      spec: gcc@=7.5.0
+      paths:
+        cc: /usr/bin/gcc
+        cxx: /usr/bin/g++
+        f77: /usr/bin/gfortran
+        fc: /usr/bin/gfortran
+      flags: {}
+      operating_system: sles15
+      target: aarch64
+      modules: []
+      environment: {}
+      extra_rpaths: []