try to make Utility.Mounts portable

This is an unholy mashup, but it just might work. It works on Linux,
that's all I've tested. :)

Utility/libmounts.h

@@ -0,0 +1,48 @@
+/* Include appropriate headers for the OS, and define what will be used. */
+#if defined(__APPLE__)
+# include <sys/param.h>
+# include <sys/ucred.h>
+# include <sys/mount.h>
+/* In newer OSX versions, statfs64 is deprecated, in favor of statfs,
+ * which is 64 bit only with a build option -- but statfs64 still works,
+ * and this keeps older OSX also supported. */
+# define GETMNTINFOCALL getmntinfo64
+# define MNTINFOSTRUCT statfs64
+#else
+#if defined (__FreeBSD__)
+# include <sys/param.h>
+# include <sys/ucred.h>
+# include <sys/mount.h>
+# define GETMNTINFOCALL getmntinfo64
+# define MNTINFOSTRUCT statfs64
+#else
+#if defined (__linux__) || defined (__FreeBSD_kernel__)
+/* Linux or Debian kFreeBSD */
+#include <mntent.h>
+# define GETMNTENT
+#else
+# warning mounts listing code not available for this OS
+# define UNKNOWN
+#endif
+#endif
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#ifndef GETMNTENT
+#warning "boo"
+struct mntent {
+	char *mnt_fsname;
+	char *mnt_dir;
+	char *mnt_type;
+	char *mnt_opts; /* not filled in */
+	int mnt_freq; /* not filled in */
+	int mnt_passno; /* not filled in */
+};
+#endif
+
+FILE *mounts_start (void);
+int mounts_end (FILE *fp);
+struct mntent *mounts_next (FILE *fp);