opencv: superres - Fix return value VideoFrameSource_GPU

opencv: superres - Fix return value VideoFrameSource_GPU

superres module fails to compile with the following error messages:

[100%] Building CXX object
modules/superres/CMakeFiles/opencv_superres.dir/src/super_resolution.cpp.o
/opencv-2.4.10/modules/superres/src/frame_source.cpp: In function
'cv::Ptr<cv::superres::FrameSource>
cv::superres::createFrameSource_Video_GPU(const string&)':
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:16: error:
expected type-specifier before 'VideoFrameSource'
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:16: error:
could not convert '(int*)operator new(4ul)' from 'int*' to
'cv::Ptr<cv::superres::FrameSource>'
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:16: error:
expected ';' before 'VideoFrameSource'
/opencv-2.4.10/modules/superres/src/frame_source.cpp:263:41: error:
'VideoFrameSource' was not declared in this scope
/opencv-2.4.10/modules/superres/src/frame_source.cpp:264:1: error:
control reaches end of non-void function [-Werror=return-type]
cc1plus: some warnings being treated as errors
make[3]: ***
[modules/superres/CMakeFiles/opencv_superres.dir/src/frame_source.cpp.o]
Error 1
make[3]: *** Waiting for unfinished jobs....

This is caused because the return value of the
createFrameSource_Video_GPU function should be a VideoFrameSource_GPU
object.

Backporting an upstream patch to fix this problem in Buildroot:
  https://github.com/Itseez/opencv/commit/2e393ab83362743ba1825ad4b31d4a2925c606b4

Fixes:
  http://autobuild.buildroot.net/results/b09/b0996267197a9016d29d6070804ebc0cb7853548/

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>