free() can handle NULL itself

Fixes ArcticaProject/nx-libs#569

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

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.

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

DO NOT USE!

The default function we use (if a thread name is not specified
explicitly) is pthread_self(). This function returns a number that is
guaranteed to be unique for each thread within a process, but this
assertion doesn't hold globally. Hence only using the thread ID is
ambiguous when logging from multiple processes.

Prevents race conditions caused by signal handlers while flushing out
our log queue.

This has one drawback: after flushing log data to its underlying output,
a new NXLogStamp object MUST be written to the NXLog object in order to
create a new entry within the stack.

This can be changed if necessary. For now I'd like to keep it as-is.

nxcomp/{configure.ac,Log.cpp}: implement configure-time std::put_time check and use macro value in Log.cpp.

This is to ensure the log output is the same as previous releases,
which didn't have INFO defined by default.

Features:
	* Works without ifdefs
	* Configurable with commandline arguments
	* Log level configurable per file
	* Thread safe

Commit 5f1eb0dc introduced a regression
that made the use of the multimedia port mandatory.

Fixes ArcticaProject/nx-libs#525

nxcomp/src/Loop.cpp: Reduce control->TokenSize slightly again in order to fix fragmentation of packages when on VPN (or otherwise encapsulated) connections.

This makes it so that slave=1 works again as it should.

The changes introduced earlier resulted in the unintentional requirement
to specify the actual port number, breaking backwards compatibility.

Fixes: ArcticaProject/nx-libs#518

nxcomp/src/{Loop,Proxy}.cpp: On Debian/kFreeBSD (and other *BSD variants) the sockaddr_un.sun_path property is 104 chars long, not 108. Hard-coding Unix domain sockets in nxcomp the string length 104.

 Fixes ArcticaProject/nx-libs#507.

nxcomp/src/Loop.cpp: Don't mix using global proxyFD and a local p(roxy)FD variable (in WaitForRemote() and ConnectToRemote()). Rename local variable name.

nxcomp/src/Loop.cpp: Don't reuse global variable names as function parameters in SetupDisplaySocket().