* Custom deep learning layers support

* Stack custom deep learning layers

  * restore resize of carotene
  * clean up the source code
  * remove unused member function (Near)
  * add strict test on the border

CPATH entries are processed before any -isystem:
https://gcc.gnu.org/onlinedocs/cpp/Environment-Variables.html

- Recommended compiler checks:
  - GCC: CV_GCC
  - Clang: CV_CLANG
- fixed problem with CMAKE_CXX_COMPILER_ID=Clang/AppleClang mess on MacOSX
  Details: cmake --help-policy CMP0025
- do not declare Clang as GCC compiler

  * disable carotenete when calling resize on ARM/Aarch64
  * loosen eps on Aarch64

FFmpeg: 3.3.4 -> 3.4.2
LibVPX: 1.6.1 -> 1.7.0
OpenH264: 1.6.0 -> 1.7.0

* Do not build protobuf if dnn is disabled

* Added BUILD_LIST cmake option to the cache

* Moved protobuf to the top level

* Fixed static build

* Fixed world build

* fixup! Fixed world build

original commit: f5035150
JavaScript bindings for dnn module

Compiler message:
tif_unix.c:170:12: error: call to 'mmap' declared with attribute error:
mmap is not available with _FILE_OFFSET_BITS=64 when using GCC until android-21.
Either raise your minSdkVersion, disable _FILE_OFFSET_BITS=64, or switch to Clang.

  - fix compilation error about "inline"
  - fix linker error about "_TIFF_snprintf_f"

  * remove non ASCII character from the comment

Implementation of bit-exact resize. Internal calls to linear resize updated to use bit-exact version. (#9468)

- 3rdparty/libjasper/jas_getopt.c:129:25: warning: this function declaration is not a prototype [-Wstrict-prototypes]
- clang: warning: optimization flag '-fomit-frame-pointer' is not supported for target 'armv7' [-Wignored-optimization-argument]