MFC r306806, r313709, r317058, r317060

r306806 by emaste:
Improvements to BSD-licensed DTC.

• Numerous crash and bug fixes
• Improved warning and error messages
• Permit multiple labels on nodes and properties
• Fix node@address references
• Add support for /delete-node/
• Consume whitespace after a node
• Read the next token before the second /memreserve/
• Fix parsing of whitespace
• Clean up /delete-node/ and add support for /delete-property/
• Handle /delete-node/ specifying a unit address

Obtained from: https://github.com/davidchisnall/dtc @df5ede4

r313709 by dim:
Fix build of BSD dtc when NDEBUG is defined (MK_ASSERT_DEBUG=no):

• Initialize correct parent in binary_operator's constructor.
• Include <errno.h> explicitly, otherwise errno is undefined (without NDEBUG, this is accidentally 'fixed' by including <iostream>).

Reported by: matteo

r317058 by emaste:
dtc: remove unused (since r306806) string.hh

r317060 by emaste:
dtc: update to upstream 227d6a3

• Report missing includes at the correct location.
• Add initial support for the -@ option emitting a symbol table.
• Add support for running tests with and without -@
• Add support for generating fixups and local_fixups
• Attach the to-string transform to the node path.