Build error on alphaev56-dec-osf4.0c

[Richard Kenner]

gcc -o c++filt -DIN_GCC    -g -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmis
sing-prototypes -Wtraditional -pedantic -Wno-long-long  -DHAVE_CONFIG_H  \
  cxxmain.o underscore.o ./intl/libintl.a  -liconv  ../libiberty/libiberty.a
/usr/bin/ld:
Unresolved:
cplus_demangle_v3_type
collect2: ld returned 1 exit status