gdb/tui: cleanup includes

Remove includes reported as unused by clangd.  Then, add any includes
necessary to get rid of errors (includes possibly relying on previous
includes)..

I didn't remove the includes of gdb-safe-ctypes.h, because it appears to
do some some preprocessor magic, redefining standard macros.  I'm afraid
that removing these includes could change the behavior unintentionally.

Change-Id: I4c5b652355c3bbce022fe0d447a72dc4e1d17d34
Approved-By: Tom Tromey <tom@tromey.com>