update discover gcc section

Author: ashley314

configs/sites/tier1/discover-scu17/packages_gcc.yaml

@@ -6,9 +6,22 @@ packages:
   mpi:
     buildable: False
   openmpi:
+    buildable: False
     externals:
     - spec: [email protected] ~cuda~cxx~cxx_exceptions~java~memchecker+pmi~static~wrapper-rpath
         fabrics=ucx schedulers=slurm
       prefix: /discover/swdev/gmao_SIteam/MPI/openmpi/4.1.6-SLES15/gcc-13.4.0
       modules:
       - mpi/openmpi/4.1.6/gcc-13.4.0
+  gcc:
+    buildable: false
+    externals:
+    - spec: [email protected] languages='c,c++,fortran'
+      prefix: /discover/swdev/gmao_SIteam/other/SLES15.4/GCC/13.4.0
+      modules:
+      - comp/gcc/13.4.0
+      extra_attributes:
+        compilers:
+          c: /discover/swdev/gmao_SIteam/other/SLES15.4/GCC/13.4.0/bin/gcc
+          cxx: /discover/swdev/gmao_SIteam/other/SLES15.4/GCC/13.4.0/bin/g++
+          fortran: /discover/swdev/gmao_SIteam/other/SLES15.4/GCC/13.4.0/bin/gfortran