This moves gdb_select.h to gdbsupport/, so it can be used by other
code there.
gdb/ChangeLog
2020-04-13 Tom Tromey <tom@tromey.com>
* gdb_select.h: Move to ../gdbsupport/.
* event-loop.c: Update include path.
* top.c: Update include path.
* ser-base.c: Update include path.
* ui-file.c: Update include path.
* ser-tcp.c: Update include path.
* guile/scm-ports.c: Update include path.
* posix-hdep.c: Update include path.
* ser-unix.c: Update include path.
* gdb_usleep.c: Update include path.
* mingw-hdep.c: Update include path.
* inflow.c: Update include path.
* infrun.c: Update include path.
* event-top.c: Update include path.
gdbsupport/ChangeLog
2020-04-13 Tom Tromey <tom@tromey.com>
* gdb_select.h: Move from ../gdb/.
