Use no mangling for all spack compiler definitions that use the XL (#8392)

Fortran compiler.
Clang can build with IBM XL Fortran compiler as well, so the name
mangling shoud be avoided for that case as well.

var/spack/repos/builtin/packages/superlu-dist/package.py

@@ -91,7 +91,8 @@ def install(self, spec, prefix):
             'INCLUDEDIR   = $(SuperLUroot)/include',
             'LOADOPTS     =',
             'CDEFS        = %s' % ("-DNoChange"
-                                       if '%xl' in spec or '%xl_r' in spec
+                                       if spack_f77.endswith('xlf') or
+                                          spack_f77.endswith('xlf_r')
                                        else "-DAdd_")
         ])