RFR: Fix tiny diff vs upstream

[Roman Kennke]

We have this little diff against upstream for no apparent reason
(probably my mistake when merging the big Shenandoah patch from upstream):

diff -r 7d6955d6d501 make/autoconf/hotspot.m4
--- a/make/autoconf/hotspot.m4  Tue Jan 08 14:53:11 2019 +0100
+++ b/make/autoconf/hotspot.m4  Mon Jan 14 11:53:02 2019 +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: hotspot_gc_shenandoah

OK?

Roman