When retry_quiet() was backported to v9_11, it was only placed in
bin/tests/system/conf.sh.in, but not in bin/tests/system/conf.sh.win32.
This prevents every system test which employs this shell function either
directly or indirectly from ever succeeding on Windows. Fix by copying
the definition of retry_quiet() to bin/tests/system/conf.sh.win32.
Michał Kępień
c9a12b8a1b