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/quotactl.cc

@@ -100,7 +100,7 @@ quotactl (int cmd, const char *special, int id, caddr_t addr)
       set_errno (ENOENT);
       return -1;
     }
-  if (!S_ISBLK (pc.dev.mode))
+  if (!S_ISBLK (pc.dev.mode ()))
     {
       set_errno (ENOTBLK);
       return -1;