gcc 4.3.3 not building avr-g++

I buiilt avr-gcc, but when I tried arduino environment it compained about not finding avr-g++. So I went back to build it. Here is my configure line for gcc-4.3.3:

gcc-4.3.3 $ ./configure --prefix=/usr/local/avr --target=avr
--enable-languages="c,c++" --disable-nls

and here is the result of ./configure

configure: error:
The following requested languages could not be built: c++
Supported languages are: c,treelang

So, whar am I doing wrong.

Slackware 13 distribution.