Windows: Fix binary output of jit.bcsave to stdout.

Thanks to erw7.

src/jit/bcsave.lua

@@ -60,6 +60,11 @@ local function savefile(name, mode)
   return check(io.open(name, mode))
 end
 
+local function set_stdout_binary(ffi)
+  ffi.cdef[[int _setmode(int fd, int mode);]]
+  ffi.C._setmode(1, 0x8000)
+end
+
 ------------------------------------------------------------------------------
 
 local map_type = {
@@ -125,6 +130,11 @@ local function bcsave_tail(fp, output, s)
 end
 
 local function bcsave_raw(output, s)
+  if output == "-" and jit.os == "Windows" then
+    local ok, ffi = pcall(require, "ffi")
+    check(ok, "FFI library required to write binary file to stdout")
+    set_stdout_binary(ffi)
+  end
   local fp = savefile(output, "wb")
   bcsave_tail(fp, output, s)
 end
@@ -568,6 +578,9 @@ end
 local function bcsave_obj(ctx, output, s)
   local ok, ffi = pcall(require, "ffi")
   check(ok, "FFI library required to write this file type")
+  if output == "-" and jit.os == "Windows" then
+    set_stdout_binary(ffi)
+  end
   if ctx.os == "windows" then
     return bcsave_peobj(ctx, output, s, ffi)
   elseif ctx.os == "osx" then