T-API: optimized UMat::copyTo with mask with dst uninitialized 

merge after https://github.com/Itseez/opencv/pull/2809

```
                    Name of Test                         old      new       new
                                                                             vs
                                                                            old
                                                                         (x-factor)
CopyToWithMask::OCL_CopyToFixture::(640x480, 8UC1)    0.234 ms  0.115 ms    2.03
CopyToWithMask::OCL_CopyToFixture::(640x480, 32FC1)   0.464 ms  0.298 ms    1.56
CopyToWithMask::OCL_CopyToFixture::(640x480, 8UC4)    0.451 ms  0.337 ms    1.34
CopyToWithMask::OCL_CopyToFixture::(640x480, 32FC4)   1.475 ms  1.240 ms    1.19
CopyToWithMask::OCL_CopyToFixture::(1280x720, 8UC1)   0.438 ms  0.232 ms    1.89
CopyToWithMask::OCL_CopyToFixture::(1280x720, 32FC1)  1.188 ms  0.899 ms    1.32
CopyToWithMask::OCL_CopyToFixture::(1280x720, 8UC4)   1.172 ms  0.914 ms    1.28
CopyToWithMask::OCL_CopyToFixture::(1280x720, 32FC4)  4.919 ms  3.224 ms    1.53
CopyToWithMask::OCL_CopyToFixture::(1920x1080, 8UC1)  0.802 ms  0.494 ms    1.62
CopyToWithMask::OCL_CopyToFixture::(1920x1080, 32FC1) 2.435 ms  1.971 ms    1.24
CopyToWithMask::OCL_CopyToFixture::(1920x1080, 8UC4)  2.540 ms  2.223 ms    1.14
CopyToWithMask::OCL_CopyToFixture::(1920x1080, 32FC4) 8.820 ms  6.671 ms    1.32
CopyToWithMask::OCL_CopyToFixture::(3840x2160, 8UC1)  3.543 ms  2.001 ms    1.77
CopyToWithMask::OCL_CopyToFixture::(3840x2160, 32FC1) 9.174 ms  6.802 ms    1.35
CopyToWithMask::OCL_CopyToFixture::(3840x2160, 8UC4)  10.115 ms 7.104 ms    1.42
```