There is a script called gdb_indent.sh in gdb's root dir. I applied
it on amd64-windows-nat.c ahead of getting out my patch thinking
that this would be the correct way. Some misunderstanding as it
produced most of your indention concerns.
That is very odd, the script should indeed indent the sources
in a way that follows the GNU Coding Standards. Perhaps we are
missing some parameters in the call to that script that override
certain defaults that may no longer match our standards. But FWIW,
we have rarely used that script in the past few years. I think
that this is because GNU indent, the tool that it uses underneath,
isn't very smart and often produces a layout that's worse than
what a human would produce.