Merge branch 'win32-filenames-cannot-have-trailing-spaces-or-periods'

On Windows, filenames cannot have trailing spaces or periods, when
opening such paths, they are stripped automatically. Read: you can open
the file `README` via the file name `README . . .`. This ambiguity can
be used in combination with other security bugs to cause e.g. remote
code execution during recursive clones. This patch series fixes that.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

diff --cc compat/mingw.c
Simple merge

diff --cc t/t7415-submodule-names.sh
Simple merge