[lldb][lldb-dap] use llvm::smallVector as gotargets are usually few

Author: da-viper

lldb/tools/lldb-dap/DAP.h

@@ -92,7 +92,7 @@ class Gotos {
   void Clear();
 
 private:
-  std::vector<lldb::SBLineEntry> line_entries;
+  llvm::SmallVector<lldb::SBLineEntry> line_entries;
 };
 
 struct Variables {