zoltan: fix building with Intel compilers (#8985)

* zoltan: fix building with Intel compilers

- building with the Intel compilers may require explicit linking
  with the Intel Fortran library (libifcore)

* simplify code; get rid of format() for static strings

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

@@ -84,7 +84,9 @@ def install(self, spec, prefix):
             config_args.append('--with-ar=$(CXX) -shared $(LDFLAGS) -o')
             config_cflags.append(self.compiler.pic_flag)
             if spec.satisfies('%gcc'):
-                config_args.append('--with-libs={0}'.format('-lgfortran'))
+                config_args.append('--with-libs=-lgfortran')
+            if spec.satisfies('%intel'):
+                config_args.append('--with-libs=-lifcore')
 
         if '+parmetis' in spec:
             config_args.append('--with-parmetis')