This patch fixes:
lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp:647:3:
error: 'llvm::Expected' may not intend to support class template
argument deduction [-Werror,-Wctad-maybe-unsupported]
lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp:677:3:
error: 'llvm::Expected' may not intend to support class template
argument deduction [-Werror,-Wctad-maybe-unsupported]