Add support for VS2015

Without the fix, OpenCV will compile and silently copy the compiled libs/executables to a location not prefixed with arch/vc14, and OpenCV won't be picked up by find_package and OpenCVConfig.cmake.

cmake/OpenCVConfig.cmake

@@ -79,6 +79,8 @@ if(MSVC)
     set(OpenCV_RUNTIME vc11)
   elseif(MSVC_VERSION EQUAL 1800)
     set(OpenCV_RUNTIME vc12)
+  elseif(MSVC_VERSION EQUAL 1900)
+    set(OpenCV_RUNTIME vc14)
   endif()
 elseif(MINGW)
   set(OpenCV_RUNTIME mingw)

cmake/OpenCVDetectCXXCompiler.cmake

@@ -140,6 +140,8 @@ if(MSVC)
     set(OpenCV_RUNTIME vc11)
   elseif(MSVC_VERSION EQUAL 1800)
     set(OpenCV_RUNTIME vc12)
+  elseif(MSVC_VERSION EQUAL 1900)
+    set(OpenCV_RUNTIME vc14)
   endif()
 elseif(MINGW)
   set(OpenCV_RUNTIME mingw)