DUNE/Time: Moved function bodies to separate .cpp file.
CMake: Added tests for mlockall() and munlockall().
DUNE/System: Protected mlockall() and munlockall() with respective test macros.
DUNE/Hardware: Removed guard from m_fd in Buttons.hpp.
DUNE/Hardware: Replaced guard DUNE_SYS_HAS_LINUX_I2C_H with DUNE_OS_LINUX in class I2C.
DUNE/Concurrency: Check macro PTHREAD_EXPLICIT_SCHED before using it in class Thread.
CMake: Added test for Android operating system.
DUNE: Added DUNE_OS_ANDROID macro.
DUNE/FileSystem: Added support for Android in class Path.
Merge branch 'feature/android'