Fix collision between keyword interface used in glibmm and windows headers
Include windows.h for Registry access related API
Use Glib::usleep in Editor::timefx_thread on Windows
Include windows.h for Sleep function
Fix pattern to match possible audio backends on windows
Always link to ole32 when building with mingw for get_win_special_folder

needed for CoTaskMemFree in get_win_special_folder
Remove duplicate test for presence of boost header
Reinstate code removed that allows building with mingw and the pthreads-win32 library

Newer versions of mingw-w64 can be built with an included pthread implementation
called winpthreads which uses an integer type for pthread_t but pthreads-win32 does
not.
Use COMPILER_MINGW define rather than __MINGW64__

This is necessary to build with win32 target using mingw-w64 version
on Fedora 19
Change windows packaging to have separate scripts for Fedora 19 and 20

A large part of the packaging is shared in package.sh, this approach should
work on windows with another dll list in package-waves.sh and redefined
copydll function(which I've added untested as copydll-waves.sh)

Also add support for 64bit mingw builds via ARCH env variable. If unset
defaults to 32bit build
Remove incorrect code for mingw in DummyAudioBackend::in_process_thread

I'm assuming this section was copied from the JackAudioBackend where the
thread type is not pthread_t for mingw, but in the DummyAudioBackend it
is.
Use Glib::usleep in DummyAudioBackend rather than ::usleep
Merge branch 'mingw-updates' of https://github.com/mojofunk/ardour into cairocanvas