Standard Linux distributions come with the GNU compiler, which can handle C, C++, Java and a few other options as well. Usually something like:
g++ -Wall -olibrary.o -c library.cpp
will create an object file from a C++ source file.
C is a "subset" of C++, much of the basic syntax is similar however C has no support for classes, overloading or the OO side of the code, so rewriting good C++ code in C is usually very timeconsuming, and in this case, there's no need.
Make sure any functions that need to be called from LabView are exported with:
extern "C" {...function prototypes...}
and you should then be able to use CINs to access C++ functions. The guide in the Labview bookshelf has more details on compiling - where it talks about C, C++ works just as well.
As a last resort, you could consider copying and pasting the code into a formula node...