The Solaris buildbot builder complained about some recent patches of
mine. Building with GCC 7 failed.
This patch fixes the bug. I'm checking it in.
gdb/ChangeLog
2019-12-13 Tom Tromey <tromey@adacore.com>
* gdbsupport/safe-iterator.h (class basic_safe_range) <begin,
end>: No longer "const".
Change-Id: I5f428fab61087f467ac3b6475f4ef4dbd314fcb0