fix some FTBFS on debian

note there are on going work packaging master branch in my sandbox/rzr/devel branch if anyone cares but this branch is debian clean and safe to be merged

It built for me using : 

    cd src/rtaudio
    ./autogen.sh  ; ./configure --target=linux --with-jack ; make
    cd - 
    ./autogen.sh  ; ./configure --target=linux  ; make
    make install


Thanks