The FindTBB.cmake module gets the TBB version by reading and grepping
one of the header files. Before doing so, it checks to see if the
version variable already exists. The problem was it was checking
TBB_VERSION, which was never created. Worse, other build systems might
set this for us (for example, the ParaView superbuild). Correct this by
making sure both TBB_VERSION_MAJOR and TBB_VERSION_MINOR are set.
In the FindTBB module, add the directory of the TBB includes and the
directory of the base tbb library to the list of paths to search for
TBB includes and libs, respectively. The reason is that TBB has its
initial includes and libraries and then has its support libraries.
Rather than enter entire paths 9 separate times, this allows you to
select the include directory once and one TBB library and the rest will
be automatically populated.
