[gn] port 9c830ce

Author: nico

llvm/utils/gn/secondary/lldb/source/Core/BUILD.gn

@@ -55,6 +55,7 @@ static_library("Core") {
     "Debugger.cpp",
     "DebuggerEvents.cpp",
     "Declaration.cpp",
+    "DemangledNameInfo.cpp",
     "Disassembler.cpp",
     "DumpDataExtractor.cpp",
     "DumpRegisterInfo.cpp",