cygwin bootstrap failure - undefined reference to `dwarf2out_init

["Billinghurst, David (CRTS)" <David dot Billinghurst at riotinto dot com>]

cygwin bootstrap fails with undefined reference to `dwarf2out_init'.  Unsure
of the correct fix.  Happy to test a patch.

gcc  -DIN_GCC    -g  -W -Wall -Wwrite-strings -Wstrict-prototypes
-Wmissing-prototypes -Wtraditional -pedantic -Wno-long-long  -DHAVE_CONFIG_H
-o cc1.exe \
	c-parse.o c-lang.o c-errors.o c-lex.o c-pragma.o c-decl.o c-typeck.o
c-convert.o c-aux-info.o c-common.o c-format.o c-semantics.o c-dump.o
libcpp.a  main.o libbackend.a obstack.o ./intl/libintl.a
../libiberty/libiberty.a
libbackend.a(dwarf2out.o): In function `dwarf2out_do_frame':
/usr/local/src/gcc-mainline/gcc/dwarf2out.c:86: undefined reference to
`dwarf2out_init'
/usr/local/src/gcc-mainline/gcc/dwarf2out.c:86: undefined reference to
`dwarf2out_finish'

Probably due to

2001-07-10  Neil Booth  <neil@daikokuya.demon.co.uk>

	* Makefile.in (toplev.o, sdbout.o, dbxout.o, dwarfout.o,
	dwarf2out.o): Depend on debug.h, wrap long lines.
	* dbxout.c: Include debug.h.
	(dbx_debug_hooks): New.
	(dbxout_init): Make static, take just 2 args.
	(dbxout_finish): Make static.
	* dbxout.h (dbxout_init, dbxout_finish): Delete.
	* debug.c: New file.
	* debug.h: New file.
	* dwarf2out.c: Include debug.h.