[gn build] Fix CodeGenTests

Missing dependency required by https://reviews.llvm.org/D67687.

Fixes
lld-link: error: undefined symbol: public: __cdecl llvm::PipelineTuningOptions::PipelineTuningOptions(void)
>>> referenced by C:\src\llvm-project\llvm\unittests\CodeGen\PassManagerTest.cpp:215
>>>               obj/llvm/unittests/CodeGen/CodeGenTests.PassManagerTest.obj:(private: virtual void __cdecl `anonymous namespace'::PassManagerTest_Basic_Test::TestBody(void))

Differential Revision: https://reviews.llvm.org/D85682

Author: aeubanks

llvm/utils/gn/secondary/llvm/unittests/CodeGen/BUILD.gn

@@ -9,6 +9,7 @@ unittest("CodeGenTests") {
     "//llvm/lib/CodeGen/SelectionDAG",
     "//llvm/lib/IR",
     "//llvm/lib/MC",
+    "//llvm/lib/Passes",
     "//llvm/lib/Support",
     "//llvm/lib/Target",
     "//llvm/lib/Target:TargetsToBuild",