Switch all open() calls to use g_open()

Because it now handles EINTR.  And we should do so.  While most people
use Linux, which tries very hard to avoid propagating EINTR back up
into userspace, it can still happen.

https://bugzilla.gnome.org/show_bug.cgi?id=682833

gobject/glib-genmarshal.c

@@ -28,6 +28,7 @@
 #endif
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <glib/gstdio.h>
 
 #undef G_LOG_DOMAIN
 #define G_LOG_DOMAIN "GLib-Genmarshal"
@@ -848,7 +849,7 @@ main (int   argc,
 	/* Mostly for Win32. This is equivalent to opening /dev/stdin */
 	fd = dup (0);
       else
-	fd = open (file, O_RDONLY);
+	fd = g_open (file, O_RDONLY, 0);
 
       if (fd < 0)
 	{