[R-SIG-Mac] libiconv missing for R-devel build

[Duncan Murdoch]

I haven't built R on Mac OS in a while, and now when I try the build 
fails with

mkdir ../../../../library/tools/libs
dyld: lazy symbol binding failed: Symbol not found: _libiconv_open
   Referenced from: /Users/murdoch/R/R-devel/lib/libR.dylib
   Expected in: flat namespace

dyld: Symbol not found: _libiconv_open
   Referenced from: /Users/murdoch/R/R-devel/lib/libR.dylib
   Expected in: flat namespace

/bin/sh: line 1: 28203 Done                    echo 
"tools:::.install_package_description('.', '"../../../library/tools"')"
      28204 Trace/BPT trap          | R_DEFAULT_PACKAGES=NULL 
../../../bin/R --vanilla --slave > /dev/null
make[3]: *** [all] Error 133
make[2]: *** [R] Error 1
make[1]: *** [R] Error 1
make: *** [R] Error 1


Looking through the configure output, I see

checking iconv.h usability... yes
checking iconv.h presence... yes
checking for iconv.h... yes
checking for iconv... no
checking for iconvlist... no
checking for iconv... no, consider installing GNU libiconv

Can anyone let me know if the advice to install libiconv is really 
correct, and if so, how to do that?  I'm on OS X 10.6.8.

Duncan Murdoch