[clang] MarkVarDeclODRUsed - remove redundant nullptr check. NFCI.

The function has already been dereferenced the Var pointer

Author: RKSimon

clang/lib/Sema/SemaExpr.cpp

@@ -17500,7 +17500,7 @@ MarkVarDeclODRUsed(VarDecl *Var, SourceLocation Loc, Sema &SemaRef,
     CaptureType, DeclRefType,
     FunctionScopeIndexToStopAt);
 
-  if (SemaRef.LangOpts.CUDA && Var && Var->hasGlobalStorage()) {
+  if (SemaRef.LangOpts.CUDA && Var->hasGlobalStorage()) {
     auto *FD = dyn_cast_or_null<FunctionDecl>(SemaRef.CurContext);
     auto VarTarget = SemaRef.IdentifyCUDATarget(Var);
     auto UserTarget = SemaRef.IdentifyCUDATarget(FD);