RFR(xs): 8144916: Decrease PerfDataMemorySize back to 32K

[Robbin Ehn]

Hi, please review.

This sets PerfDataMemorySize back to 32k and
removes "-XX:PerfDataMemorySize=64k" in PrologSizeSanityCheck test.

Bug: https://bugs.openjdk.java.net/browse/JDK-8144916
Webrev: http://cr.openjdk.java.net/~redestad/8144916

Testing:
JPRT testset hotspot and
PrologSizeSanityCheck with -XX:CICompilerCount=256 works fine.

Thanks!

/Robbin