title: CMake does not properly find CUDA library
body: <p>I'm trying to build a program that requires CUDA. To the CMake script I supply:</p>
  
  <pre><code>cmake -D CUDA_TOOLKIT_ROOT_DIR=/usr/local/cuda ..
  </code></pre>
  
  <p>CUDA is found and CMake runs normally:</p>
  
  <pre><code>staudt ~/workspace/clutbb/cluster/build $ cmake -D CUDA_TOOLKIT_ROOT_DIR=/usr/local/cuda ..                                                                                  
  -- Found CUDA: /usr/local/cuda (found version "6.5") 
  -- Found Intel TBB
  -- Boost version: 1.56.0
  -- Found the following Boost libraries:
  --   iostreams
  --   program_options
  -- Looking for include file pthread.h
  -- Looking for include file pthread.h - found
  -- Looking for pthread_create
  -- Looking for pthread_create - not found
  -- Looking for pthread_create in pthreads
  -- Looking for pthread_create in pthreads - not found
  -- Looking for pthread_create in pthread
  -- Looking for pthread_create in pthread - found
  -- Found Threads: TRUE  
  -- Could NOT find SDL (missing:  SDL_LIBRARY SDL_INCLUDE_DIR) 
  -- Configuring done
  -- Generating done
  -- Build files have been written to: /home/i11/staudt/workspace/clutbb/cluster/build
  </code></pre>
  
  <p>But then the linker step fails:</p>
  
  <pre><code>staudt ~/workspace/clutbb/cluster/build $ make
  [ 69%] Built target cluster
  Linking CXX executable clu
  CMakeFiles/clu.dir/clu.cpp.o: In function `initCUDA(int&amp;, CUctx_st*&amp;, int const&amp;)':
  clu.cpp:(.text+0x517): undefined reference to `cuInit'
  clu.cpp:(.text+0x52b): undefined reference to `cuDeviceGet'
  clu.cpp:(.text+0x53f): undefined reference to `cuCtxCreate_v2'
  clu.cpp:(.text+0x559): undefined reference to `cuDeviceGetName'
  clu.cpp:(.text+0x55e): undefined reference to `cuCtxSynchronize'
  CMakeFiles/clu.dir/clu.cpp.o: In function `exitCUDA(int&amp;, CUctx_st*&amp;)':
  clu.cpp:(.text+0x684): undefined reference to `cuCtxDestroy_v2'
  CMakeFiles/clu.dir/clu.cpp.o: In function `main':
  clu.cpp:(.text.startup+0x1092): undefined reference to `cuCtxDestroy_v2'
  clu.cpp:(.text.startup+0x10d1): undefined reference to `cuCtxSynchronize'
  clu.cpp:(.text.startup+0x10e1): undefined reference to `cuCtxSynchronize'
  collect2: error: ld returned 1 exit status
  make[2]: *** [bin/clu] Fehler 1
  make[1]: *** [bin/CMakeFiles/clu.dir/all] Fehler 2
  make: *** [all] Fehler 2
  </code></pre>
  
  <p>The required library is at <code>/usr/local/cuda/lib64/stubs/libcuda.so</code>, but how can I point that out to cmake or make?</p>