Fixing IssueHash generation.
There were some problems with the current version.
If the Decl *D pointer is nullptr the NormalizeLine would crash while getting the LangOptions. The required LangOptions can be provided by the HTML or Plist Diagnostics.
It is possible that the column number provided by the find_first_not_of is 0 in that case the Lexer reads up a wrong source line (translateLineCol requires that column numbering should start at 1).
I think there should be an assert checking the line and col values in the sourcemanagers translateLineCol. The same way as in translateFileLineCol which does this check.