Update copyright year range in gdb.ada/mi_ref_changeable testcase

Update copyright year range in gdb.ada/mi_ref_changeable testcase

This patch fixes the copyright year range which escaped
the 2019 update, because the patch was submitted in 2018, but
only really pushed in 2019.

    Pushed: https://www.sourceware.org/ml/gdb-patches/2019-02/msg00109.html
    Submitted: https://www.sourceware.org/ml/gdb-patches/2018-12/msg00444.html

We normally are pretty good at remembering those little things,
but this one fell through the cracks. This commit fixes this,
by re-running the copyright.py script and checking in the changes
made by that script.

gdb/testsuite/ChangeLog:

	* gdb.ada/mi_ref_changeable.exp: Update copyright year range.
	* gdb.ada/mi_ref_changeable/foo_rb20_056.adb: Likewise.
	* gdb.ada/mi_ref_changeable/pck.adb: Likewise.
	* gdb.ada/mi_ref_changeable/pck.ads: Likewise.
	* gdb.dwarf2/inlined_subroutine-inheritance.exp: Likewise.