[gn build] Port 50c4e03

Author: llvmgnsyncbot

llvm/utils/gn/secondary/clang/unittests/Tooling/BUILD.gn

@@ -59,6 +59,7 @@ unittest("ToolingTests") {
     "RecursiveASTVisitorTests/Concept.cpp",
     "RecursiveASTVisitorTests/ConstructExpr.cpp",
     "RecursiveASTVisitorTests/DeclRefExpr.cpp",
+    "RecursiveASTVisitorTests/DeductionGuide.cpp",
     "RecursiveASTVisitorTests/ImplicitCtor.cpp",
     "RecursiveASTVisitorTests/ImplicitCtorInitializer.cpp",
     "RecursiveASTVisitorTests/InitListExprPostOrder.cpp",