Fixes ArcticaProject/nx-libs#547.

 Fixes ArcticaProject/nx-libs#546.

Attributes GH PR #579: https://github.com/ArcticaProject/nx-libs/pull/579

Some functions' return values are never used anywhere, so drop them.

This corrects a flaw that stayed undetected for 2.5 years, introduced via
c5a2cf82

Fixes ArcticaProject/nx-libs#573

Attributes GH PR #556: https://github.com/ArcticaProject/nx-libs/pull/556

Adds a new option called "keyconv" to control keycode conversion.

Before commit 2f2ade61 keycode
conversion was activated if the client was Linux and client side rules
and/or model was "evdev". The only (and undocumented) way to disable
that was providing a value different from "linux" for the "client"
option (which had no other effect). The mentioned commit removed the
dependency on Linux and so there was no way anymore to disable keycode
conversion.

Attributes GH PR #563: https://github.com/ArcticaProject/nx-libs/pull/563

Was missed in
GH PR #544: https://github.com/ArcticaProject/nx-libs/pull/544

Fixes: ArcticaProject/nx-libs#536

Attributes GH PR #555: https://github.com/ArcticaProject/nx-libs/pull/555

nxagentGetClientsPath() allocated and returned a string that was never
used anywhere because it also fills the global variable with the same
value.

free() can handle NULL so there's no need to check this ourselves

Attributes GH PR #554: https://github.com/ArcticaProject/nx-libs/pull/554

Commit 3f7b3001 was incomplete: the
options parameter was not parsed as a string on reconnect. It was
always assumed to be a filename.

Attributes GH PR #532: https://github.com/ArcticaProject/nx-libs/pull/532

This change make the code more similar to upstream Xorg which helps
when merging in changes from later Xorg releases.

This has also been done in Xorg 7.1

This also fixes a little flaw for the swapped case: a check for
glXRenderLarge was missing.

Attributes GH PR #552: https://github.com/ArcticaProject/nx-libs/pull/552

delete trailing whitespace, break long lines, always emphasize nxagent
and nxproxy, emphassize options identcially everywhere

Attributes GH PR #544: https://github.com/ArcticaProject/nx-libs/pull/544

Fixes: ArcticaProject/nx-libs#536

Allowing overrides via NX_TEMP and TEMP breaks system using
pam_tmpdir.so and most server infrastructure expects the location to be
fixed anyway.

Attributes GH PR #543: https://github.com/ArcticaProject/nx-libs/pull/543

Works around libtool bug related to using both -nostdlib and -pthread
(with the former dropping latter usage.)

Regression fix for f855b3b6. Caused FTBFS with Loop.cpp:2669:0: error: unterminated #ifdef (#ifdef TIME).

Attibutes GH PR #302: https://github.com/ArcticaProject/nx-libs/pull/302

Attributes GH PR #193: https://github.com/ArcticaProject/nx-libs/pull/193