Only add -msse4.2 if it is supported by the compiler

[cottsay]

Using CMake's check_cxx_compiler_flag(), determine if the compiler supports -msse4.2 and add it only if it does.

The primary motivation is that the flag is not supported on ARM platforms for obvious reasons, and causes the build to fail. This is currently (01/02/2015) the only Jade package not building on ARM in Fedora.

The check does output the result to the console so it can be verified that it is working correctly. Look for GCC_HAS_SSE.

Example ARM build failure: http://csc.mcs.sdsmt.edu/jenkins/job/ros-jade-ecto-opencv_binaryrpm_21_armhfp/1/consoleFull
Example ARM build after patch: http://csc.mcs.sdsmt.edu/jenkins/job/ros-jade-ecto-opencv_binaryrpm_21_armhfp/3/consoleFull
Example x86 build after patch: http://csc.mcs.sdsmt.edu/jenkins/job/ros-jade-ecto-opencv_binaryrpm_21_x86_64/3/consoleFull

Thanks,

--scott

[vrabaud]

Hi, though your pull request is totally valid (and thx for showing me that !), this SSE check is actually useless as that code has been moved to opencv_candidate (which actually does not need that flag anymore). I'll make a new release for you. Thx !