Patch #5: This patch does the following:
- Removes HAVE_CRYPT_H, HAVE_CXXABI_H, HAVE_SYNCH_H, HAVE_SYS_MALLOC_H,
  HAVE_SYS_PRCTL_H, HAVE_ASM_TERMBITS_H, HAVE_TERMCAP_H, HAVE_UTIME_H,
  HAVE_SYS_UTIME_H. The header they check for is not needed.
- Removes the inclusion of several system header files that is not needed.
- Moves inclusion of serveral system header files from header files to impl files.
- Removes serveral unneeded extern "C" blocks.
- Uses HAVE_xxx checks consistently when including system headers.
- Removes NEED_EXPLICITY_SYNC_DIR - only used in one file. Replaced with __linux__
- Changes many timespec macros to inline functions, removes dead code.
- Adds a missing header guard.