upgrade zlib to 1.2.11

An ino_t is usually a 64 bit integer, and some file systems (such as
Linux's kernel NFS client) really uses the upper 32 bit.  This can
lead to false positives in the directory loop detection in
FindAncestorLoop().  Increasing these two attributes (in
StorageFileInfo and Directory) to 64 bit adds little overhead, but
makes the check a lot safer.

The TAG_MODIFIED handler (i.e. playlist::TagModified()) works only if
the modified song is the current song - something that is not updated
until SYNC_WITH_PLAYER is finished.  This fixes tag updates right
after a new song is started.

https://bugs.musicpd.org/view.php?id=4665

Just in case.

GCC7 outputs the following error without this change:

    src/util/ReusableArray.hxx:61:35: error: no matching function for call to ‘swap(size_t&, const size_t&)’
       std::swap(capacity, src.capacity);

which can be resolved by just using an rvalue-reference rather than a
const rvalue-reference.
Signed-off-by: Ben Boeckel <mathstuf@gmail.com>

Android is migrating away from GCC, and libstdc++ will disappear
eventually.

This repairs the damage to commit 74dbaade done by commit
b3f5b493

Fixes a GCC warning because %llu appears to be unsupported by the
Windows standard library.

https://bugs.musicpd.org/view.php?id=4656 describes a crash due to
division by zero because frame.samples==0.  This should never happen,
but apparently can happen after seeking.  The best we can do is to
just ignore this frame.

Allow multiple arguments.

Fixes another buffer overflow: if the stream has a very long title or
URL, resulting in a metadata string of more than 2 kB, icy_string[0]
is a negative value, which gets casted to size_t - ouch!

 https://bugs.musicpd.org/view.php?id=4652

Fixes a buffer overflow due to the bad formula rounding the buffer
size up.  At the same time, remove the "+1" from the meta_length
calculation, which takes the padding into account and at the same time
implements proper rounding.

Why did this cast exist??

Yet another potential crash bug fix.

Fixes build breakage by commit 4e5271fc; and this method does make
sense in non-debug builds.

Fixes potential crash bug.

Now ClearSocketList() may only be called from PrepareSockets().
Calling it before destroying the object doesn't work properly, because
it doesn't unregister the TimeoutMonitor and the IdleMonitor.  Some of
its callers need to be fixed.