configure: don't give an example including an equals sign
configure: don't give an example including an equals sign

We can't handle --prefix=foo (we need --prefix foo instead).
So don't give the former as an example.

Signed-off-by: Colin McCabe <3142ce8a0bdba4a38073365893e6b74f72d9c512@alumni.cmu.edu>

cmccabe/lksmith,cmccabe/lksmith