Assume TERMIOS is default, remove TERMIO on all Linux.

The rationale for this move is that TERMIOS is default, supported by
POSIX-1.2001, and most definitely on Linux.  For a few other systems,
TERMIO may still be the termnial interface of preference, so we keep
-DTERMIO on those in Configure.

crypto/ui/ui_openssl.c is simplified in this regard, and will define
TERMIOS for all systems except a select few exceptions.
Reviewed-by: NMatt Caswell <matt@openssl.org>

crypto/ui/ui_openssl.c

@@ -178,43 +178,36 @@
 
 /*
  * There are 5 types of terminal interface supported, TERMIO, TERMIOS, VMS,
- * MSDOS and SGTTY
+ * MSDOS and SGTTY.
+ *
+ * If someone defines one of the macros TERMIO, TERMIOS or SGTTY, it will
+ * remain respected.  Otherwise, we default to TERMIOS except for a few
+ * systems that require something different.
+ *
+ * Note: we do not use SGTTY unless it's defined by the configuration.  We
+ * may eventually opt to remove it's use entirely.
  */
 
-#if defined(__sgi) && !defined(TERMIOS)
-# define TERMIOS
-# undef  TERMIO
-# undef  SGTTY
-#endif
-
-#if defined(linux) && !defined(TERMIO)
-# undef  TERMIOS
-# define TERMIO
-# undef  SGTTY
-#endif
+#if !defined(TERMIOS) && !defined(TERMIO) && !defined(SGTTY)
 
-#ifdef _LIBC
+# if defined(_LIBC)
 #  undef  TERMIOS
 #  define TERMIO
 #  undef  SGTTY
-#endif
-
-#if !defined(TERMIO) && !defined(TERMIOS) && !defined(OPENSSL_SYS_VMS) && !defined(OPENSSL_SYS_MSDOS) && !defined(MAC_OS_GUSI_SOURCE)
-# undef  TERMIOS
-# undef  TERMIO
-# define SGTTY
-#endif
-
-#if defined(OPENSSL_SYS_VXWORKS)
-# undef TERMIOS
+/*
+ * We know that VMS, MSDOS, VXWORKS, NETWARE use entirely other mechanisms.
+ * MAC_OS_GUSI_SOURCE should probably go away, but that needs to be confirmed.
+ */
+# elif !defined(OPENSSL_SYS_VMS) \
+	&& !defined(OPENSSL_SYS_MSDOS) \
+	&& !defined(MAC_OS_GUSI_SOURCE) \
+	&& !defined(OPENSSL_SYS_VXWORKS) \
+	&& !defined(OPENSSL_SYS_NETWARE)
+#  define TERMIOS
 #  undef  TERMIO
 #  undef  SGTTY
-#endif
+# endif
 
-#if defined(OPENSSL_SYS_NETWARE)
-# undef TERMIOS
-# undef TERMIO
-# undef SGTTY
 #endif
 
 #ifdef TERMIOS