ocl: disable OpenCL by default for Android builds

CMakeLists.txt

@@ -161,7 +161,7 @@ OCV_OPTION(WITH_MSMF           "Build VideoIO with Media Foundation support" OFF
 OCV_OPTION(WITH_XIMEA          "Include XIMEA cameras support"               OFF  IF (NOT ANDROID) )
 OCV_OPTION(WITH_XINE           "Include Xine support (GPL)"                  OFF  IF (UNIX AND NOT APPLE AND NOT ANDROID) )
 OCV_OPTION(WITH_CLP            "Include Clp support (EPL)"                   OFF)
-OCV_OPTION(WITH_OPENCL         "Include OpenCL Runtime support"              ON   IF (NOT IOS) )
+OCV_OPTION(WITH_OPENCL         "Include OpenCL Runtime support"              NOT ANDROID IF (NOT IOS) )
 OCV_OPTION(WITH_OPENCL_SVM     "Include OpenCL Shared Virtual Memory support" OFF ) # experimental
 OCV_OPTION(WITH_OPENCLAMDFFT   "Include AMD OpenCL FFT library support"      ON   IF (NOT ANDROID AND NOT IOS) )
 OCV_OPTION(WITH_OPENCLAMDBLAS  "Include AMD OpenCL BLAS library support"     ON   IF (NOT ANDROID AND NOT IOS) )