Minor grammar improvements to documentation
Assorted fixes:

* cmake CMP0054 and CMP0045
* aarch64 build
* portable code options in PCH cmake
* some of gcc 4.9 warnings
Fix Android build with the most resent android.toolchain.cmake
fix tests for gpu::matchTemplate:

use ASSERT_FLOAT_EQ to compare float values, it is more robust for
large values
Merge pull request #3545 from jet47:gpu-match-template-tests
Merge pull request #3543 from MatMoore:2.4
Merge pull request #3534 from taka-no-me:build_fixes
Fix of HaarCascade GPU test for aarch64.
TBB updated to 4.3u2. Fix for aarch64 support.
Full AARCH64 support with NEON and new CUDA toolkit.
More accurate fix for libtiff and aarch64.