Handle up to 63 partitions per drive

Revamp device parsing code.  Introducing support for more partitions
into the shilka-generated parser has the unfortunate side-effect of
raising the size of the DLL by almost 2 Megs.  Therefore we split out
the handling for /dev/sdXY devices into a tiny bit of hand-written
code.

While at it, remove some unused cruft from devices.* and generally
clean up the device class to provide access methods instead of direct
access to members.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/mount.cc

@@ -78,7 +78,7 @@ win32_device_name (const char *src_path, char *win32_path, device& dev)
   dev.parse (src_path);
   if (dev == FH_FS || dev == FH_DEV)
     return false;
-  strcpy (win32_path, dev.native);
+  strcpy (win32_path, dev.native ());
   return true;
 }