RFR(XS) 8032894: Remove dead code in Pressure::lower

[Niclas Adlertz]

Hi all,

When building the physical IFG, we step backwards in each block, and 
remove things that are defined from the LIVE_OUT, (and lower the current 
pressure) and add input to the LIVE_OUT (and raising the current 
pressure). Each time we lower or raise the current pressure, we check if 
it's bigger than the current maximum pressure, known as final_pressure. 
However the final_pressure can never increase when removing definitions 
(i.e. lower the current pressure) so the check for a new final_pressure 
in Pressure::lower is useless.

webrev: http://cr.openjdk.java.net/~adlertz/JDK-8032894/webrev00/
bug: https://bugs.openjdk.java.net/browse/JDK-8032894

Kind Regards,
Niclas Adlertz