SIGWINCH is not XPG6 compatible

SIGWINCH is not part of the X/Open <signal.h>
specification.
Switch to c99 signal()

Don't try to use non-c99 compliant sigaction
stuff; we don't need it anyway.
C99: Mark POSIX source files

Specifly POSIX standard for every source
file that needs it.

Hide term_t structure inside src/io/term.c
not to expose POSIX (struct timespec) to client.

Remove unnecessary #include "io/term.h"
C99: Mark POSIX source files

Specifly POSIX standard for every source
file that needs it.

Hide term_t structure inside src/io/term.c
not to expose POSIX (struct timespec) to client.

Remove unnecessary #include "io/term.h"
Move SIGWINCH code into awinch.c
Merge branch 'strdup' into c99
cfg_parser.y does not use fileno(2)
Get rid of POSIX fileno(2) in flex output

Flex generated code checks if the input
file is a terminal using isatty(2) and fileno(2).

We don't need that as we always pass either string
buffer or a disk file.
Merge branch 'c99' of git://github.com/saper/em400 into saper-c99
non-verbose cmake, remove fprintf()