Add CV_16UC1 support for cuda::CLAHE

Due to size limit of shared memory, histogram is built on
the global memory for CV_16UC1 case.

The amount of memory needed for building histogram is:

    65536 * 4byte = 256KB

and shared memory limit is 48KB typically.

Added test cases for CV_16UC1 and various clip limits.
Added perf tests for CV_16UC1 on both CPU and CUDA code.

There was also a bug in CV_8UC1 case when redistributing
"residual" clipped pixels. Adding the test case where clip
limit is 5.0 exposes this bug.

modules/core/include/opencv2/core/cuda_types.hpp

@@ -127,10 +127,12 @@ namespace cv
         };
 
         typedef PtrStepSz<unsigned char> PtrStepSzb;
+        typedef PtrStepSz<unsigned short> PtrStepSzus;
         typedef PtrStepSz<float> PtrStepSzf;
         typedef PtrStepSz<int> PtrStepSzi;
 
         typedef PtrStep<unsigned char> PtrStepb;
+        typedef PtrStep<unsigned short> PtrStepus;
         typedef PtrStep<float> PtrStepf;
         typedef PtrStep<int> PtrStepi;