Recently I've done `emerege -e world` and then found that `gcc` was compiled without `cxx` flag. Now I can't compile any C++ package due to

    configure: error: C++ preprocessor "/lib/cpp" fails sanity check

I'm thinking on copying files returned by `equery f gcc|grep -v share
` from stage3. Will it help? Is there any simpler way?

Here's `config.log`
        uhradio ~ # cat /var/tmp/portage/dev-util/gperf-3.0.4/work/gperf-3.0.4/config.log
        This file contains any messages produced by compilers while
        running configure, to aid debugging if configure makes a mistake.

        It was created by configure, which was
        generated by GNU Autoconf 2.61.  Invocation command line was

        $ ./configure --prefix=/usr --build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu --mandir=/usr/share/man --infodir=/usr/share/info --datadir=/usr/share --sysconfdir=/etc --localstatedir=/var/lib --libdir=/usr/lib64

        ## --------- ##
        ## Platform. ##
        ## --------- ##

        hostname = uhradio
        uname -m = x86_64
        uname -r = 3.6.11-gentoo
        uname -s = Linux
        uname -v = #2 SMP Thu Jan 24 08:55:22 Local time zone must be set--see zic

        /usr/bin/uname -p = Intel(R) Xeon(R) CPU X3360 @ 2.83GHz
        /bin/uname -X     = unknown

        /bin/arch              = unknown
        /usr/bin/arch -k       = unknown
        /usr/convex/getsysinfo = unknown
        /usr/bin/hostinfo      = unknown
        /bin/machine           = unknown
        /usr/bin/oslevel       = unknown
        /bin/universe          = unknown

        PATH: /usr/lib64/ccache/bin
        PATH: /usr/lib64/portage/bin/ebuild-helpers
        PATH: /usr/local/sbin
        PATH: /usr/local/bin
        PATH: /usr/sbin
        PATH: /usr/bin
        PATH: /sbin
        PATH: /bin
        PATH: /opt/bin
        PATH: /usr/x86_64-pc-linux-gnu/gcc-bin/4.6.3


        ## ----------- ##
        ## Core tests. ##
        ## ----------- ##

        configure:1609: checking whether make sets $(MAKE)
        configure:1630: result: yes
        configure:1797: creating ./config.status

        ## ---------------------- ##
        ## Running config.status. ##
        ## ---------------------- ##

        This file was extended by config.status, which was
        generated by GNU Autoconf 2.61.  Invocation command line was

        CONFIG_FILES    =
        CONFIG_HEADERS  =
        CONFIG_LINKS    =
        CONFIG_COMMANDS =
        $ ./config.status

        on uhradio

        config.status:566: creating Makefile
        configure:2728: === configuring in lib (/var/tmp/portage/dev-util/gperf-3.0.4/work/gperf-3.0.4/lib)
        configure:2831: running /bin/sh ./configure '--prefix=/usr'  '--build=x86_64-pc-linux-gnu' '--host=x86_64-pc-linux-gnu' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--datadir=/usr/share' '--sysconfdir=/etc' '--localstate dir=/var/lib' '--libdir=/usr/lib64' 'build_alias=x86_64-pc-linux-gnu' 'host_alias=x86_64-pc-linux-gnu' --cache-file=/dev/null --srcdir=.
        configure:2836: error: ./configure failed for lib
        ## ---------------- ##
        ## Cache variables. ##
        ## ---------------- ##

        ac_cv_env_build_alias_set=set
        ac_cv_env_build_alias_value=x86_64-pc-linux-gnu
        ac_cv_env_host_alias_set=set
        ac_cv_env_host_alias_value=x86_64-pc-linux-gnu
        ac_cv_env_target_alias_set=
        ac_cv_env_target_alias_value=
        ac_cv_prog_make_make_set=yes

        ## ----------------- ##
        ## Output variables. ##
        ## ----------------- ##

        DEFS='-DPACKAGE_NAME=\"\" -DPACKAGE_TARNAME=\"\" -DPACKAGE_VERSION=\"\" -DPACKAGE_STRING=\"\" -DPACKAGE_BUGREPORT=\"\"'
        ECHO_C=''
        ECHO_N='-n'
        ECHO_T=''
        LIBOBJS=''
        LIBS=''
        LTLIBOBJS=''
        PACKAGE_BUGREPORT=''
        PACKAGE_NAME=''
        PACKAGE_STRING=''
        PACKAGE_TARNAME=''
        PACKAGE_VERSION=''
        PATH_SEPARATOR=':'
        SET_MAKE=''
        SHELL='/bin/sh'
        bindir='${exec_prefix}/bin'
        build_alias='x86_64-pc-linux-gnu'
        datadir='/usr/share'
        datarootdir='${prefix}/share'
        docdir='${datarootdir}/doc/${PACKAGE}'
        dvidir='${docdir}'
        exec_prefix='${prefix}'
        host_alias='x86_64-pc-linux-gnu'
        htmldir='${docdir}'
        includedir='${prefix}/include'
        infodir='/usr/share/info'
        libdir='/usr/lib64'
        libexecdir='${exec_prefix}/libexec'
        localedir='${datarootdir}/locale'
        localstatedir='/var/lib'
        mandir='/usr/share/man'
        oldincludedir='/usr/include'
        pdfdir='${docdir}'
        prefix='/usr'
        program_transform_name='s,x,x,'
        psdir='${docdir}'
        sbindir='${exec_prefix}/sbin'
        sharedstatedir='${prefix}/com'

        subdirs=' lib src tests doc'
        sysconfdir='/etc'
        target_alias=''