New build break on OS X

[Thor Lancelot Simon <tls%panix.com@localhost>]

For the past several days, building on OS X 10.9.5 has failed with what
looks like a symptom of host/target confusion that could have more serious
consequences (like bad builds on other platforms).  This is new.  Hubert
has also seen it on OS X 10.5.

Build command is "build.sh -m amd64 -U -u distribution".  Happens in a
clear (non-update) build too.

#      link  backend/genmatch
c++ -O
-I/Volumes/NB/build-src/external/gpl3/gcc/usr.bin/host-libiberty/obj/libiberty
-I.
-I/Volumes/NB/build-src/external/gpl3/gcc/usr.bin/backend/../gcc/arch/x86_64
-DIN_GCC -DHAVE_CONFIG_H -I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/.
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/../include
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/../libcpp/include
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/../libdecnumber
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/../libdecnumber/dpd
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/../libbacktrace
-DGENERATOR_FILE -I/Volumes/NB/build-src/external/gpl3/gcc/usr.bin/backend/..
-o genmatch genmatch.lo build-errors.lo build-vec.lo build-hash-table.lo
-L/Volumes/NB/build-src/obj/tooldir.Darwin-13.4.0-x86_64/lib -lnbcompat
/Volumes/NB/build-src/external/gpl3/gcc/usr.bin/host-libcpp/obj/libcpp/libcpp.a
/Volumes/NB/build-src/external/gpl3/gcc/usr.bin/host-libiberty/obj/libiberty/libiberty.a
Undefined symbols for architecture x86_64:
  "_iconv", referenced from:
      convert_using_iconv(void*, unsigned char const*, unsigned long,
_cpp_strbuf*) in libcpp.a(charset.o)
     (maybe you meant: __Z14cpp_init_iconvP10cpp_reader, __cpp_destroy_iconv )
  "_iconv_close", referenced from:
      __cpp_destroy_iconv in libcpp.a(charset.o)
      __cpp_convert_input in libcpp.a(charset.o)
  "_iconv_open", referenced from:
      init_iconv_desc(cpp_reader*, char const*, char const*) in
libcpp.a(charset.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see
invocation)

*** Failed target:  genmatch
*** Failed command: c++ -O
-I/Volumes/NB/build-src/external/gpl3/gcc/usr.bin/host-libiberty/obj/libiberty
-I.
-I/Volumes/NB/build-src/external/gpl3/gcc/usr.bin/backend/../gcc/arch/x86_64
-DIN_GCC -DHAVE_CONFIG_H -I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/.
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/../include
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/../libcpp/include
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/../libdecnumber
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/../libdecnumber/dpd
-I/Volumes/NB/build-src/external/gpl3/gcc/dist/gcc/../libbacktrace
-DGENERATOR_FILE -I/Volumes/NB/build-src/external/gpl3/gcc/usr.bin/backend/..
-o genmatch genmatch.lo build-errors.lo build-vec.lo build-hash-table.lo
-L/Volumes/NB/build-src/obj/tooldir.Darwin-13.4.0-x86_64/lib -lnbcompat
/Volumes/NB/build-src/external/gpl3/gcc/usr.bin/host-libcpp/obj/libcpp/libcpp.a
/Volumes/NB/build-src/external/gpl3/gcc/usr.bin/host-libiberty/obj/libiberty/libiberty.a
*** Error code 1

Stop.
nbmake[8]: stopped in /Volumes/NB/build-src/external/gpl3/gcc/usr.bin/backend
/bin/sh: line 1: 46823 Segmentation fault: 11
/Volumes/NB/build-src/obj/tooldir.Darwin-13.4.0-x86_64/bin/nbmake
_THISDIR_="${this}" "$@" ${target}

*** Failed target:  dependall-backend
*** Failed command: _makedirtarget() { dir="$1"; shift; target="$1"; shift;
case "${dir}" in /*) this="${dir}/"; real="${dir}" ;; .)
this="external/gpl3/gcc/usr.bin/";
real="/Volumes/NB/build-src/external/gpl3/gcc/usr.bin" ;; *)
this="external/gpl3/gcc/usr.bin/${dir}/";
real="/Volumes/NB/build-src/external/gpl3/gcc/usr.bin/${dir}" ;; esac;
show=${this:-.}; echo "${target} ===> ${show%/}${1:+ (with: $@)}"; cd
"${real}" && /Volumes/NB/build-src/obj/tooldir.Darwin-13.4.0-x86_64/bin/nbmake
_THISDIR_="${this}" "$@" ${target}; }; _makedirtarget backend dependall
*** Error code 139

Stop.
nbmake[7]: stopped in /Volumes/NB/build-src/external/gpl3/gcc/usr.bin