gdb: add callback defines for new ARGV handling

The common sim code has slightly unfinished support for these already,
but even arch ports are unable to handle these if the common header does
not define them.  This is because the generated callback header includes
simple common gdb/sim headers only which causes it to skip the new ARGV
syscalls.  Plus, it isn't like providing these in the common header will
break any sim targets which don't want them.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

include/gdb/ChangeLog

@@ -1,3 +1,7 @@
+2012-04-12  Mike Frysinger  <vapier@gentoo.org>
+
+	* callback.h (CB_SYS_argc, CB_SYS_argnlen, CB_SYS_argn): Define.
+
 2012-02-03  Kevin Buettner  <kevinb@redhat.com>
 
 	* sim-rl78.h: New file.

include/gdb/callback.h

@@ -231,6 +231,11 @@ extern host_callback default_callback;
 #define CB_SYS_truncate	21
 #define CB_SYS_ftruncate 22
 #define CB_SYS_pipe 	23
+
+/* New ARGV support.  */
+#define CB_SYS_argc	24
+#define CB_SYS_argnlen	25
+#define CB_SYS_argn	26
 
 /* Struct use to pass and return information necessary to perform a
    system call.  */