libdfp: Function left_justify fixed for PPC/DPD.

Added a check to left_justify function in order to catch when the
number justified would become a NaN data. This patch also adds tests
to verify this.
libdecnumber: Fix potentially out of the bound array access

decGetInt can potentially acess a out of the bounds value from array
DECPOWERS, this patch fixes the test to actually access the array.
Function left_justify fixed for x86/BID.

Added a check to left_justify function in order to catch when the
number justified would become a NaN number, like is done for PPC
with hardware instructions.

This patch also fixes get_digits[32|64|128] to handle NaN numbers.
libdfp: Add not equal to BID hack alias
libdfp: Fix test internal buffer size
libdfp: Fix NaN1/mask definition for LE/DPD

This patch fixes the NaN1 mask definition on left_justify for LE and
also corrects a compiler warning triggered by issuing memset with size
of 0.
bdfp: Fix setexpd[32|64|128] for x86/BID.

Fixed setexp functions to correctly handle when small numbers overflow
because the exponent.