Merge 2.4 into master

Original pull requests:

* #2097 from pclove1:blur_border_isolated
* #2205 from jet47:bug-3477-fix
* #2209 from asmorkalov:ocv_test_install
* #2215 from asmorkalov:ocv_testpack_fix
* #2221 from asmorkalov:ocv_test_install_custom
* #2224 from SpecLad:obsolete-immediate
* #2229 from ilya-lavrenov:possible_memory_leak
* #2231 from asmorkalov:android_toolchain_update
* #2238 from asmorkalov:ocv_test_package_reports
* #2240 from jet47:gpu-generalized-hough
* #2241 from asmorkalov:ocv_highgui_test_output_fix
* #2242 from jet47:gpu-test-fix
* #2247 from jet47:gpu-test-cufft
* #2248 from jet47:gpu-npp-disable
* #2249 from jet47:gpu-tests-disable