nx-X11/config/cf/{gnu,lnx}Lib.rules: add RPATH entries for temporary nxcomp and nxcompshad libraries.

No change to the actually installed relinked nxagent(-relink) binary
that gets installed - only affects the temporary executable build
binary.

Attributes GH PR #623: https://github.com/ArcticaProject/nx-libs/pull/623

Fixes: ArcticaProject/nx-libs#616

nxcomp/src/Timestamp.{cpp,h}: use ::ctime_s or ::ctime_r instead of plain ctime, on-stack buffers and return std::string objects.

Fixes: ArcticaProject/nx-libs#616

Attributes GH PR #629: https://github.com/ArcticaProject/nx-libs/pull/629

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.