Fixes ArcticaProject/nx-libs#991

Attributes GH PR #994: https://github.com/ArcticaProject/nx-libs/pull/994

Make it obvious that GetWindowProperty() and ChangeWindowProperty are
not derived from dix.

by calling the dix version after a check

remove unneccessary parentheses

make it compile again

Thanks to Simon Matter for reporting this and the patch.

Fixes ArcticaProject/nx-libs#993

debian/patches: Drop 2002_xserver-xext_set-securitypolicy-path.debian.patch. Not required anymore since 689f811b.

 Regression fix.

Attributes GH PR #989: https://github.com/ArcticaProject/nx-libs/pull/989

We can now also drop all remaining NX specific lines from the security.c

see ArcticaProject/nx-libs#988

This reflects the path where the file is placed after installation.

It also obsoletes the NX_ALTERNATIVEPOLICYFILE.

Fixes ArcticaProject/nx-libs#988

Attributes GH PR #990: https://github.com/ArcticaProject/nx-libs/pull/990

Fixes ArcticaProject/nx-libs#987

Attributes GH PR #982: https://github.com/ArcticaProject/nx-libs/pull/982

Is required for compilations with musl.

See ArcticaProjects/nx-libs#975 and ArcticaProjects/nx-libs#976

Fixes ArcticaProject/nx-lib#975

Attributes GH PR #981: https://github.com/ArcticaProject/nx-libs/pull/981

This used to be printed only in TEST mode. Some while ago I had
changed that to WARNING (because it is a warning...). However, this
happens e.g. when running the xscreensaver vfeedback module and it
does not look like it is a problem at all. So let's suppress this
warning again and leave it to the TEST mode as it used to be.

although there is no functional difference...

Attributes GH PR #979: https://github.com/ArcticaProject/nx-libs/pull/979

PVS finding: "V522 There might be dereferencing of a potential null pointer 'props'"

PVS finding: "V522 There might be dereferencing of a potential null pointer 'nxagentConfiguredWindowList'."

PVS finding: "V522 There might be dereferencing of a potential null pointer"

PVs finding: "V547 Expression '!nxagentWMPassed' is always true."

"V547 Expression 'wmHints.input == 1' is always true."

PVS Studio: "V614 Potentially uninitialized variable 'glyphBox.*' used."

"V701 realloc() possible leak: when realloc() fails in allocating
memory, original pointer 'nxagentReconnectErrorMessage' is
lost. Consider assigning realloc() to a temporary pointer."