Attributes GH PR #628: https://github.com/ArcticaProject/nx-libs/pull/628

Fixes: ArcticaProject/nx-libs#589

Got dropped by accident in 9bc6ff26

Fixes ArcticaProject/nx-libs#589

Attributes GH PR #567: https://github.com/ArcticaProject/nx-libs/pull/567

even if we issue a FatalError afterwards

I am not sure about the maximum font name length in X but just in
case use snprintf instead of memcpy to be sure nothing dangerous can
happen here.

This is a partial copy from XlibInt.c's _XPrintDefaultError, which had
some minor changes since being copied. Update to reflect these
changes. Also comment some more lines as their result was unused an
cluttered the output.

and insert one single space

Also comment the code and convert error messages to warnings.

Fix write past the end of singlePath if PATH contains dirs longer than PATH_MAX.

Attributes GH PR #614: https://github.com/ArcticaProject/nx-libs/pull/614

Fixes: ArcticaProject/nx-libs#610

Will only be useful at build time, since installation strips any
RPATH/RUNPATH again.

Using libtool, the nxproxy binary will be replaced by a shell script
wrapper that correctly pulls in required libraries (like libXcomp), thus
making it possible to start the binary directly in the build directory.

This wrapper is dropped during installation time.

This is a C program, so enabling or disabling C++11 support will not do
anything useful.

At most it'll lead to errors when using libtool, which is the next
change to come...

We need this to be able to execute the resulting nxagent binary from
within the build directory.

nx-X11: build programs with a temporary RPATH/RUNPATH value and a relinked version with the system location.

While the install target explicitly installs the relinked
system-location version of a program, we do not actually use this.

Currently, we copy nxagent directly out of the build root.