Include <fcntl.h> unconditionally.

Include <fcntl.h> unconditionally.
* src/termcap.c:
* src/sysdep.c:
* src/lread.c:
* src/keyboard.c:
* src/filelock.c:
* src/fileio.c:
* src/doc.c:
* src/callproc.c:
* src/alloc.c: Remove include guards for <fcntl.h>, process.c already
does it.