[Ada] Add some OS constants to control serial port

[Pierre-Marie de Rodat]

This adds some OS constants that are needed to control the serial port
on GNU/Linux.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

        * s-oscons-tmplt.c: Add some OS constants.
diff --git a/gcc/ada/s-oscons-tmplt.c b/gcc/ada/s-oscons-tmplt.c
--- a/gcc/ada/s-oscons-tmplt.c
+++ b/gcc/ada/s-oscons-tmplt.c
@@ -724,6 +724,41 @@ CNU(CRTSCTS, "Output hw flow control")
 #endif
 CNU(CREAD, "Read")
 
+#ifndef ICANON
+# define ICANON -1
+#endif
+CNU(ICANON, "canonical mode")
+
+#ifndef CBAUD
+# define CBAUD -1
+#endif
+CNU(CBAUD, "baud speed mask")
+
+#ifndef ECHO
+# define ECHO -1
+#endif
+CNU(ECHO, "echo input characters")
+
+#ifndef ECHOE
+# define ECHOE -1
+#endif
+CNU(ECHOE, "erase preceding characters")
+
+#ifndef ECHOK
+# define ECHOK -1
+#endif
+CNU(ECHOK, "kill character, erases current line")
+
+#ifndef ECHOCTL
+# define ECHOCTL -1
+#endif
+CNU(ECHOCTL, "echo special characters")
+
+#ifndef ECHONL
+# define ECHONL -1
+#endif
+CNU(ECHONL, "force echo NL character")
+
 #ifndef CS5
 # define CS5 -1
 #endif