[Gc] Bug in build instructions

On the page http://www.hboehm.info/gc/, under the heading "Where to get  
the collector", there is a shell excerpt:

    cd D
    git clone git://github.com/ivmai/libatomic_ops.git
    git clone git://github.com/ivmai/bdwgc.git
    ln -s  D/libatomic_ops D/bdwgc/libatomic_ops
    cd bdwgc
    autoreconf -vif
    automake --add-missing
    ./configure
    make

The fourth line refers to directory D in a relative path, even though the  
first line cd'd into it.

Maybe add a "pushd .." and "popd" around line 4.

Sam Nipps