[LV] Fix value that could be read uninitialized.

This should fix
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-bootstrap-msan/builds/18569

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -6908,7 +6908,7 @@ VPWidenCallRecipe *VPRecipeBuilder::tryToWidenCall(Instruction *I,
     // The flag shows whether we use Intrinsic or a usual Call for vectorized
     // version of the instruction.
     // Is it beneficial to perform intrinsic call compared to lib call?
-    bool NeedToScalarize;
+    bool NeedToScalarize = false;
     unsigned CallCost = CM.getVectorCallCost(CI, VF, NeedToScalarize);
     bool UseVectorIntrinsic =
         ID && CM.getVectorIntrinsicCost(CI, VF) <= CallCost;