Fix unit tests after r296049.

llvm-svn: 296055
diff --git a/llvm/unittests/DebugInfo/PDB/PDBApiTest.cpp b/llvm/unittests/DebugInfo/PDB/PDBApiTest.cpp
index cd0f928..ba09a8e 100644
--- a/llvm/unittests/DebugInfo/PDB/PDBApiTest.cpp
+++ b/llvm/unittests/DebugInfo/PDB/PDBApiTest.cpp
@@ -63,7 +63,7 @@
 class MockSession : public IPDBSession {
   uint64_t getLoadAddress() const override { return 0; }
   void setLoadAddress(uint64_t Address) override {}
-  std::unique_ptr<PDBSymbolExe> getGlobalScope() const override {
+  std::unique_ptr<PDBSymbolExe> getGlobalScope() override {
     return nullptr;
   }
   std::unique_ptr<PDBSymbol> getSymbolById(uint32_t SymbolId) const override {