title: Cmake not applying compile option using add_compile_options
body: <p>im trying to use cmake with the following compile options using add_compile_options : <code>add_compile_options(-pipe -O2 -std=c++98 -W -Wall -pedantic)</code></p>
  
  <p>But it does not seem to be actually used during the compilation.</p>
  
  <p><code>make -n | grep pedantic</code> does not return anything</p>
  
  <p>Just for information, my cmake command and what it returns :</p>
  
  <pre><code>cmake -G"Unix Makefiles" -DARCH:STRING=x86 -Bosef -H. -DCMAKE_C_COMPILER=/usr/bin/gcc -DCMAKE_CXX_COMPILER=/usr/bin/g++
  -- The C compiler identification is GNU 4.8.3
  -- The CXX compiler identification is GNU 4.8.3
  -- Check for working C compiler: /usr/bin/gcc
  -- Check for working C compiler: /usr/bin/gcc -- works
  -- Detecting C compiler ABI info
  -- Detecting C compiler ABI info - done
  -- Check for working CXX compiler: /usr/bin/g++
  -- Check for working CXX compiler: /usr/bin/g++ -- works
  -- Detecting CXX compiler ABI info
  -- Detecting CXX compiler ABI info - done
  -- cmake run for linux x86
  -- Configuring done
  -- Generating done
  -- Build files have been written to: /home/davidlevy/WS/LC4/main/osef
  </code></pre>
  
  <p>What can I do to actually have the options applied?</p>
  
  <p>PS : I noticed they were not applied because make does not output a single warning</p>
  
  <p>EDIT : If instead I use </p>
  
  <pre><code>set (
    CMAKE_CXX_FLAGS
    "${CMAKE_CXX_FLAGS} "
    "${CMAKE_CXX_FLAGS} -pipe -O2 -std=c++98 -W -Wall -pedantic"
  )
  </code></pre>
  
  <p>Make does <code>/usr/bin/g++    ; -pipe -O2 -std=c++98 -W -Wall -pedantic -I ENDOFTHECOMMAND</code> I dont know where does this ; comes from</p>