SPIRV: Fix compilation in NDEBUG.

(cherry picked from commit 59351fe)

Author: jyknight

llvm/lib/Target/SPIRV/SPIRVDuplicatesTracker.cpp

@@ -70,6 +70,7 @@ void SPIRVGeneralDuplicatesTracker::buildDepsGraph(
     }
   }
 
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
   if (MMI) {
     const Module *M = MMI->getModule();
     for (auto F = M->begin(), E = M->end(); F != E; ++F) {
@@ -92,4 +93,5 @@ void SPIRVGeneralDuplicatesTracker::buildDepsGraph(
       }
     }
   }
+#endif
 }