Fix XGMI detection (#699)

* Fix XGMI detection

* Increase stack size

* Temporarily disable signal hangler in CI

[Process: 17281] Inside handler function signal: Segmentation fault (11)
BFD: DWARF error: section .debug_info is larger than its filesize! (0x93ef57 vs 0x530ea0)
BFD: DWARF error: section .debug_info is larger than its filesize! (0x93ef57 vs 0x530ea0)

src/graph/search.cc

@@ -1187,7 +1187,7 @@ ncclResult_t ncclTopoGetLinkType(struct ncclTopoSystem* system, int cudaDev1, in
           struct ncclTopoNode* remNode = link->remNode;
           if (remNode->gpu.dev == cudaDev2) {
             *isXGMI = (link->type == LINK_NVL);
-            return ncclSuccess;
+            if (*isXGMI) return ncclSuccess;
           }
         }
       }