On Debian and Fedora, TBB is only available on amd64 and ia64. In order to improve portability, here is a patch to add OpenMP pragmas. A new --enable-openmp configure option is added to enable those pragmas when compiling with Autotools. Due to a bug in libtool (it strips down -fopenmp flag when linking), a workaround is included, but works only when compiling with GNU g++.
On Windows, it should work out of the box after enabling OpenMP support in Visual projects.