RFR [8u]: ShenandoahSATBBufferSize cannot be size_t in 8u

[Aleksey Shipilev]

This is 8u-specific. We cannot have the size_t flag here, because it would not be settable without:
  https://bugs.openjdk.java.net/browse/JDK-8054823

The attempt to set it would fail with "Improperly specified VM option: -XX:ShenandoahSATBBufferSize=1K".

Fix:

diff -r d215450bcdca -r 3355d7c81b7b src/share/vm/gc_implementation/shenandoah/shenandoah_globals.hpp
--- a/src/share/vm/gc_implementation/shenandoah/shenandoah_globals.hpp  Mon Nov 12 18:02:02 2018 +0100
+++ b/src/share/vm/gc_implementation/shenandoah/shenandoah_globals.hpp  Mon Nov 12 18:31:06 2018 +0100
@@ -235,7 +235,7 @@
   experimental(bool, ShenandoahWriteBarrierCsetTestInIR, true,              \
           "Perform cset test in IR rather than in the stub")                \
                                                                             \
-  experimental(size_t, ShenandoahSATBBufferSize, 1 * K,                     \
+  experimental(intx, ShenandoahSATBBufferSize, 1 * K,                       \
           "Number of entries in an SATB log buffer.")                       \
                                                                             \
   product_rw(int, ShenandoahRegionSamplingRate, 40,                         \


Testing: tier1_gc_shenandoah, ad-hoc tests

Thanks,
-Aleksey