Drop outdated FindTBB.cmake module

[badshah400]

The FindTBB.cmake module is outdated as TBB does not supply a "tbb_stddef.h" header any more. This leads to build failures as seen here:

[   22s] -- Could NOT find MPI_CXX (missing: MPI_CXX_LIB_NAMES MPI_CXX_HEADER_DIR MPI_CXX_WORKS) 
[   22s] -- Could NOT find MPI (missing: MPI_C_FOUND MPI_CXX_FOUND) 
[   23s] -- Found OpenMP_C: -fopenmp (found version "4.5") 
[   23s] -- Found OpenMP_CXX: -fopenmp (found version "4.5") 
[   23s] -- Found OpenMP: TRUE (found version "4.5")  
[   23s] CMake Error at cmake/FindTBB.cmake:187 (file):
[   23s]   file failed to open for reading (No such file or directory):
[   23s] 
[   23s]     /usr/include/tbb/tbb_stddef.h
[   23s] Call Stack (most recent call first):
[   23s]   examples/CMakeLists.txt:6 (find_package)
[   23s] 
[   23s] 
[   23s] -- Found TBB: /usr/include (found version ".")  

The fix is straightforward: just drop the FindTBB.cmake file, which will allow cmake to look for and use TBB upstream's supplied cmake modules directly. I have tested that this works as expected.

Thanks.

[rabauke]

@badshah400 : Thanks for this issue report.