This commit applies all changes made after running the gdb/copyright.py
script.
Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.
gdb/ChangeLog:
Update copyright year range in all GDB files.
Make gdb aware of the return values of functions which
return in registers.
gdb/ChangeLog:
* s12z-tdep.c (s12z_extract_return_value): New function.
(inv_reg_perm) New array.
(s12z_return_value): Populate readbuf if non-null.
