btl/openib: fix #if vs #ifdef

(back-ported from commit open-mpi/ompi@d5a2ac6)

Conflicts:
	opal/mca/btl/openib/btl_openib_component.c

Author: ggouaillardet

opal/mca/btl/openib/btl_openib_component.c

@@ -780,7 +780,7 @@ static int init_one_port(opal_list_t *btl_list, mca_btl_openib_device_t *device,
 #if HAVE_DECL_IBV_ATOMIC_HCA
             openib_btl->atomic_ops_be = false;
 
-#if HAVE_STRUCT_IBV_EXP_DEVICE_ATTR_EXT_ATOM
+#ifdef HAVE_STRUCT_IBV_EXP_DEVICE_ATTR_EXT_ATOM
             /* check that 8-byte atomics are supported */
             if (!(device->ib_exp_dev_attr.ext_atom.log_atomic_arg_sizes & (1<<3ull))) {
                 openib_btl->super.btl_flags &= ~MCA_BTL_FLAGS_ATOMIC_FOPS;