export CFLAGS="-march=i486 -mtune=i686 -Os -pipe"
export CXXFLAGS="-march=i486 -mtune=i686 -Os -pipe -fno-exceptions -fno-rtti"
export PKG_CONFIG_PATH=/usr/lib/pkgconfig:/usr/local/lib/pkgconfig

bison-2.4.1
-----------

$ ./configure --prefix=/usr/local

$ make
$ sudo make install