This commit is the result of running the gdb/copyright.py script,
which automated the update of the copyright year range for all
source files managed by the GDB project to be updated to include
year 2023.
This commit brings all the changes made by running gdb/copyright.py
as per GDB's Start of New Year Procedure.
For the avoidance of doubt, all changes in this commits were
performed by the script.
In some situations it is possible that a user might not want GDB to
try and access source code files, for example, the source code might
be stored on a slow to access network file system.
It is almost certainly possible that using some combination of 'set
directories' and/or 'set substitute-path' a user can trick GDB into
being unable to find the source files, but this feels like a rather
crude way to solve the problem.
In this commit a new option is add that stops GDB from opening and
reading the source files. A user can run with source code reading
disabled if this is required, then re-enable later if they decide
that they now want to view the source code.
