...
checking for nl_langinfo's argument to obtain the codeset... CODESET
checking for namespace support... no
configure: error: Namespace support is required to build ICU.
*** Error code 1

Stop.
make[1]: stopped in /usr/pkgsrc/textproc/icu
*** Error code 1

configure:3792: checking for a BSD-compatible install
configure:3860: result: /usr/bin/install -c -o makoto -g wheel
configure:3892: c++ -o conftest -O2 -I/usr/include -I/usr/include 
     -L/usr/lib -Wl,-R/usr/lib -Wl,-R/usr/pkg/lib conftest.cpp  >&5
/usr/bin/ld: cannot find -lc++
clang: error: linker command failed with exit code 1 (use -v to see invocation)

This does not happen with clang-3.3. clang-3.4 has a problem like this.

livorno@makoto 07:42:26/140215(..textproc/icu)% cat  ~/prep/c++-test.cpp
/* confdefs.h */
#define PACKAGE_NAME ""
#define PACKAGE_TARNAME ""
#define PACKAGE_VERSION ""
#define PACKAGE_STRING ""
#define PACKAGE_BUGREPORT ""
#define PACKAGE_URL ""
/* end confdefs.h.  */

int
main ()
{

  ;
  return 0;
}

This is not only with clang-3.4, but clang-3.3 also suffers.