Fix Linux build when io.h is available

Bug 40953 - fail compile git: make[2]: *** [hb_view-options.o] Error 1
diff --git a/configure.ac b/configure.ac
index e1b6bf8..ac41742 100644
--- a/configure.ac
+++ b/configure.ac
@@ -52,7 +52,7 @@
 GTK_DOC_CHECK([1.15],[--flavour no-tmpl])
 
 # Functions and headers
-AC_CHECK_FUNCS(mprotect sysconf getpagesize mmap)
+AC_CHECK_FUNCS(mprotect sysconf getpagesize mmap _setmode)
 AC_CHECK_HEADERS(unistd.h sys/mman.h io.h)
 
 # Compiler flags
diff --git a/util/options.cc b/util/options.cc
index a923a98..fe2feaf 100644
--- a/util/options.cc
+++ b/util/options.cc
@@ -439,8 +439,8 @@
       /* read it */
       GString *gs = g_string_new (NULL);
       char buf[BUFSIZ];
-#ifdef HAVE_IO_H
-      _setmode (fileno (stdin), O_BINARY);
+#ifdef HAVE__SETMODE
+      _setmode (fileno (stdin), _O_BINARY);
 #endif
       while (!feof (stdin)) {
 	size_t ret = fread (buf, 1, sizeof (buf), stdin);
@@ -579,8 +579,8 @@
   if (output_file)
     fp = fopen (output_file, "wb");
   else {
-#ifdef HAVE_IO_H
-    _setmode (fileno (stdout), O_BINARY);
+#ifdef HAVE__SETMODE
+    _setmode (fileno (stdout), _O_BINARY);
 #endif
     fp = stdout;
   }