Refactor code to check for terminal sharing

This refactors the code to check for terminal sharing.
is_gdb_terminal is exported, and sharing_input_terminal_1 is renamed,
slightly refactored, and moved to posix-hdep.c.  A new
Windows-specific implementation of this function is added to
mingw-hdep.c.

MSDN has a warning about GetConsoleProcessList

    This API is not recommended and does not have a virtual terminal
    equivalent. [...] Applications remoting via cross-platform
    utilities and transports like SSH may not work as expected if
    using this API.

However, we believe this isn't likely to be an issue for gdb.

1 files changed, 11 insertions, 0 deletions

diff --git a/gdb/inferior.h b/gdb/inferior.h
index 69525a2..547e875 100644
--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -167,6 +167,17 @@ extern void default_print_float_info (struct gdbarch *gdbarch,
 				      frame_info_ptr frame,
 				      const char *args);
 
+/* Try to determine whether TTY is GDB's input terminal.  Returns
+   TRIBOOL_UNKNOWN if we can't tell.  */
+
+extern tribool is_gdb_terminal (const char *tty);
+
+/* Helper for sharing_input_terminal.  Try to determine whether pid
+   PID is using the same TTY for input as GDB is.  Returns
+   TRIBOOL_UNKNOWN if we can't tell.  */
+
+extern tribool sharing_input_terminal (int pid);
+
 extern void child_terminal_info (struct target_ops *self, const char *, int);
 
 extern void child_terminal_ours (struct target_ops *self);