gptune: fix build by setting compilers to mpi wrappers (#28235)

var/spack/repos/builtin/packages/gptune/package.py

@@ -65,6 +65,9 @@ def cmake_args(self):
             libs.joined(";"),
             '-DCMAKE_Fortran_FLAGS=' + ''.join(fc_flags),
             '-DBUILD_SHARED_LIBS=ON',
+            '-DCMAKE_CXX_COMPILER=%s' % spec['mpi'].mpicxx,
+            '-DCMAKE_C_COMPILER=%s' % spec['mpi'].mpicc,
+            '-DCMAKE_Fortran_COMPILER=%s' % spec['mpi'].mpifc,
         ]
 
         return args