[aarch64-port-dev ] [URGENT] RFR (XS): Adjust code stub sizes for Shenandoah and future backports

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/8u-codestub-sizes/webrev.01/

This is the unnumbered fix, because it is specific to Shenandoah 8u. I prefer to fix it right in
integration forest to unblock testing. Current testing shows that Windows x86_64 fastdebug build
cannot start with -XX:+UseShenandoahGC, because code stubs are too small to fit Shenandoah code. It
is enough to fit the same code on Linux, though.

So, we need to adjust it. Upstream code made multiple adjustments over the years, and I would prefer
not to second-guess that, and just pick up the values from current jdk/jdk:
  http://hg.openjdk.java.net/jdk/jdk/file/17f24c0e2f01/src/hotspot/cpu/x86/stubRoutines_x86.hpp#l34

http://hg.openjdk.java.net/jdk/jdk/file/17f24c0e2f01/src/hotspot/cpu/aarch64/stubRoutines_aarch64.hpp#l42

Testing: Shenandoah tests on {x86_64} x {Linux, Windows} x {release, fastdebug, slowdebug}

-- 
Thanks,
-Aleksey