Increase test coverage of C code [AP-949] (#1377) #1392

Job	Run time
Test Big Endian	19m 52s
macOS	38m 34s
Ubuntu 18.04 (Build: Debug, Compilers: gcc-6/g++-6, Shared Library: true)	15m 39s
Ubuntu 18.04 (Build: Debug, Compilers: clang-6.0/clang++-6.0, Shared Library: true)	14m 11s
Ubuntu 18.04 (Build: Debug, Compilers: clang-6.0/clang++-6.0, Shared Library: false)	14m 20s
Ubuntu 18.04 (Build: Release, Compilers: gcc-6/g++-6, Shared Library: true)	21m 55s
Ubuntu 18.04 (Build: Release, Compilers: gcc-6/g++-6, Shared Library: false)	22m 32s
Ubuntu 18.04 (Build: Release, Compilers: clang-6.0/clang++-6.0, Shared Library: true)	20m 10s
Ubuntu 18.04 (Build: Release, Compilers: clang-6.0/clang++-6.0, Shared Library: false)	20m 51s
Bazel	6m 31s
Windows 2019 (Generator: MinGW Makefiles, Shared Library: true)	26m 50s
Windows 2019 (Generator: MinGW Makefiles, Shared Library: false)	26m 22s
Windows 2019 (Generator: Visual Studio 16 2019, Shared Library: true)	9m 6s
Windows 2019 (Generator: Visual Studio 16 2019, Shared Library: false)	9m 4s
	4h 25m 57s

Provide feedback