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/pinfo.cc

@@ -449,7 +449,7 @@ _pinfo::_ctty (char *buf)
     {
       device d;
       d.parse (ctty);
-      __small_sprintf (buf, "ctty %s", d.name);
+      __small_sprintf (buf, "ctty %s", d.name ());
     }
   return buf;
 }