For everyone interested :
On 64 bit debian systems you need to install the X11 compatibility libraries with
sudo apt-get install libx11-dev:i386
sudo apt-get install libxext-dev:i386
The same syntax is for the other libraries mentioned by David necessary.
Afterwards it compiles without problems and 9vx runs like a charm. I could compile programs and edit sourcefiles in the host translate under plan9 and its really fast.
Thanks David and everyone involved in 9vx and vx32 thats what I need to write software for plan9.