Merge branch 'js/mingw-assign-comma-fix'

The "return errno = EFOO, -1" construct, which is heavily used in
compat/mingw.c and triggers warnings under "-Wcomma", has been
rewritten to avoid the warnings.

* js/mingw-assign-comma-fix:
  mingw: avoid the comma operator

diff --cc compat/mingw.c
Simple merge