The clang/libc++ version in xcode10.3 does not support C++17 properly
and cannot build MPD.

The old "ppa:mstipicevic/ninja-build-1-7-2" just provides ninja 1.7
which is too old and breaks the build.

This enables the JACK output plugin on Windows, but doesn't link
against libjack64.dll, instead loads the DLL at runtime with
LoadLibrary().  This kludge avoids the extremely fragile JACK shared
memory protocol by using the system's libjack64.dll, without requiring
the same DLL at build time.

Fixes crash when pausing the default partition after an output was
moved to another partition.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1147

This reverts commit 1532983f.  This
optimization was bad because now all strings match if they are a
prefix of another string, and this caused collisions in the tag string
pool, corrupting the database.

Upcoming release of game-music-emu will support it, details here: https://bitbucket.org/mpyne/game-music-emu/pull-requests/23/rsn-support

The current http output doesn't provide a header for cross-origin support. This prevents to use the mpd http stream directly from an other webapplication due the origin from the webpage differs from then the audio stream.

The fix is to add the following header to the http response:
Access-Control-Allow-Origin: *

Calling consume_all() is illegal in the producer thread.

Fixes bogus Delay() results at the start of playback, because Delay()
thinks the output is paused.

Fixes a bogus assertion failure (which can now be removed).

Instead of generating silence, do nothing, don't waste CPU time.

This code is complicated - and broken: the producer thread is not
allowed to call consumer methods.  Also the code is not necessary
because this plugin implements Interrupt().

OpenDevice was a confusing name because it does not actually open a
device.

Postpone the Start() call until there is something to be played.

This finishes problems which occur early in the WasapiOutputThread;
previously, the error was ignored and the output blocked forever
without doing anything (and without reporting the error).