RFR (XS) 8215356: Disable x86_32 Shenandoah build to avoid hotspot/tier1 failures

[Aleksey Shipilev]

Bug;
  https://bugs.openjdk.java.net/browse/JDK-8215356

There are lots of hotspot/tier1 tests on x86_32 caused by Shenandoah. This mode is experimental, and
we can disable it without prejudice to make tests clean. Once x86_32 support is fixed, we can
re-enable it back.

Fix:

diff -r 748cab25d902 -r f9d158363d15 make/autoconf/hotspot.m4
--- a/make/autoconf/hotspot.m4  Thu Dec 13 14:39:16 2018 +0100
+++ b/make/autoconf/hotspot.m4  Thu Dec 13 14:48:30 2018 +0100
@@ -327,7 +327,7 @@

   # Only enable Shenandoah on supported arches
   AC_MSG_CHECKING([if shenandoah can be built])
-  if test "x$OPENJDK_TARGET_CPU_ARCH" = "xx86" || test "x$OPENJDK_TARGET_CPU" = "xaarch64" ; then
+  if test "x$OPENJDK_TARGET_CPU" = "xx86_64" || test "x$OPENJDK_TARGET_CPU" = "xaarch64" ; then
     AC_MSG_RESULT([yes])
   else
     DISABLED_JVM_FEATURES="$DISABLED_JVM_FEATURES shenandoahgc"

Testing: x86_64 tier1_gc_shenandoah, x86_32 hotspot/tier1.

Thanks,
-Aleksey