shared library name is .so and not .so.2

[mathog]

A problem with velocyto was traced to numba and its interaction with this tbb package. Details here:

velocyto-team/velocyto.py#269

In short, numba (and possibly others) look for "libtbb.so.2", but the cmake build of this tbb only creates "libtbb.so". Renaming the shared libraries from this build from .so to .so.2, then making links to the .so.2 version from the .so version resolved this issue. Ditto for the other two other shared libraries it made.

Older libtbb versions, such as those on CentOS 8, all seem to all have that naming convention.