This is not a functional change, it only helps in clearer debugging
output.

The second parameter was always NULL, so remove it. Also remove some
debugging output which distracts while debugging as the function is
called from ProcChangeProperty for _every_ property, also non-clipboard
related ones.

we reference lastSelectionOwner[nxagentClipboardSelection].selection everywhere.

nxagentClipboardAtom -> serverCLIPBOARD
nxagentTimestampAtom -> serverTIMESTAMP

This is to match the names of the other server atom variables.

At some places we were using NumCurrentSelections. We replace that by
nxagentMaxSelections because they always have the identical value.

Just as everyone else does. ICCCM is not really clear about this.

endTransfer is the only caller

fixup! Clipboard.c: introduce XSendNotificationEventHelper

There was only one place where this was checked but we check it always.

Attributes GH PR #827: https://github.com/ArcticaProject/nx-libs/pull/827

One cannot simply pass down a va_list to another function that expects
variable arguments ("..."). The prototype of the called functions must
expect a va_list argument instead.

This fixes segfaults that happen e.g. after compiling X11.cpp with
TEST and effectively reverts 59e829f3.

by reformatting comments and removing blank lines.

It is not dependent on any root window and needs only be called once on
startup.

nxagentTriangles
nxagentTriFan
nxagentTriStrip

Improve code readability

Save some lines...

make the code more readable

This way we can remove lots of #ifdef DEBUGs

also drop unused return code