This fixes the following:
```
[6603/7618] Building CXX object
tools\lldb\source\Plugins\ObjectFile\PECOFF\CMakeFiles\lldbPluginObjectFilePECOFF.dir\WindowsMiniDump.cpp.obj
C:\src\git\llvm-project\lldb\source\Plugins\ObjectFile\PECOFF\WindowsMiniDump.cpp(29,25):
warning: object backing the pointer will be destroyed at the end of the
full-expression [-Wdangling-gsl]
29 | const auto &outfile = core_options.GetOutputFile().value();
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
```