Limit unit tests check to 7 digits precision

Limit unit tests check to 7 digits precision

Note that 8 digits is not enough a reduction:

on hurd-i386: echo "3.417131125e-02" | perl -p -e 's/([-+]?\d\.\d+e[-+]\d+)/sprintf("%0.8e",$1)/ge'
3.41713112e-02

on armel: echo "3.417131125e-02" | perl -p -e 's/([-+]?\d\.\d+e[-+]\d+)/sprintf("%0.8e",$1)/ge'
3.41713113e-02