fix Issue 12163 - pdb debugging (win64): stepping loops points to incorr...

...ect lines

https://issues.dlang.org/show_bug.cgi?id=12163
Why isn't endloc not needed by the DoStatement?

See also https://github.com/D-Programming-Language/dmd/pull/2867 for a similar change. It also saves endloc for the ScopeStatement.