Fix quantize test inputs
Fix quantize test inputs

The expected output for -0.1, 1.0 should be -0.1.

Another test is added to get the expected value of -0 by reducing
the precision of the second input.

Signed-off-by: Paul E. Murphy <bcb79dc2d3103f301c432ff2685f8b89fad82826@linux.vnet.ibm.com>

gftg85/libdfp,pmur/libdfp,pmur/libdfp,pmur/libdfp,gftg85/libdfp,gftg85/libdfp,gftg85/libdfp,pmur/libdfp