Revert "[NFC] Fix a gcc build break by not using an initializer."

This reverts commit 1dc0a85.

Reason: Dependency of patch that broke the ASan buildbots:
  http://lab.llvm.org:8011/#/builders/5/builds/2269

llvm/lib/CodeGen/AsmPrinter/PseudoProbePrinter.cpp

@@ -62,7 +62,7 @@ void PseudoProbeHandler::emitPseudoProbe(uint64_t Guid, uint64_t Index,
     uint64_t CallerGuid = Names[Name];
     uint64_t CallerProbeId = PseudoProbeDwarfDiscriminator::extractProbeIndex(
         InlinedAt->getDiscriminator());
-    ReversedInlineStack.emplace_back(CallerGuid, CallerProbeId);
+    ReversedInlineStack.push_back({CallerGuid, CallerProbeId});
     InlinedAt = InlinedAt->getInlinedAt();
   }