Windows: 32bit package does not register as 64bit postmortem debugger

qtcdebugger -register only creates an entry for the WoW64 node as it is a 32bit executable (the problematic part is that it ships with a 64bit Qt package).

Looking at the code of "Support accessing 32-bit Registry from 64-bit programs and vice versa" 64261c0871043ef44a0a9c855d78428e773dfa94 (qtbase/5.7) https://codereview.qt-project.org/#/c/121446/ and http://msdn.microsoft.com/en-us/library/aa384129%28VS.85%29.aspx , it should actually be possible to access both registry sections.

It could either be reimplemented in terms of QSettings using the new Registry32/64Format (5.7) or use WinAPI.