package/opencv: fix build failure on x86

This change adds a patch fixing some opencv asm causing build failures on
i*86 with PIC.

This patch has been sent upstream [1].

Fixes:
  http://autobuild.buildroot.org/results/483/4838285b25d6293a5cf0bb9eadd5040a7c75d766/
  http://autobuild.buildroot.org/?reason=opencv-2.4.10&&arch=i686

[1] https://github.com/Itseez/opencv/pull/3331



Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>