RFR: Disable ShenandoahCompileCheck by default

[Aleksey Shipilev]

There seem to be upstream compiler errors [1] that make our nightlies unhappy with
ShenandoahCompileCheck begin trueInDebug. Let's demote it to false:

diff -r 35f51ec57ad7 src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp
--- a/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp    Mon Aug 06 16:49:07 2018 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoah_globals.hpp    Wed Aug 08 09:49:59 2018 +0200
@@ -421,9 +421,9 @@
           "Tracing task termination timings")                               \
                                                                             \
   diagnostic(bool, ShenandoahElasticTLAB, true,                             \
           "Use Elastic TLABs with Shenandoah")                              \
                                                                             \
-  diagnostic(bool, ShenandoahCompileCheck, trueInDebug,                     \
+  diagnostic(bool, ShenandoahCompileCheck, false,                           \
           "Assert that methods are successfully compilable")                \

 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAH_GLOBALS_HPP

Testing: tier1_gc_shenandoah

Thanks,
-Aleksey

[1] http://mail.openjdk.java.net/pipermail/shenandoah-dev/2018-August/007023.html