RFR(XS) 8226404,bootcycle build uses wrong CDS archive

[Ioi Lam]

https://bugs.openjdk.java.net/browse/JDK-8226404

When doing "make bootcycle-images", we would attempt to use the newly built
JDK with a CDS archive generated by the BOOT_JDK. This could cause the build
to fail (the underlying cause is JDK-8226406 "JVM fails to detect mismatched
or corrupt CDS archive").

Here's a simple fix (to override the -Xshare:auto specified in spec.gmk.in):

$ hg diff ./autoconf/bootcycle-spec.gmk.in
diff -r d57d61aafef9 make/autoconf/bootcycle-spec.gmk.in
--- a/make/autoconf/bootcycle-spec.gmk.in    Thu Jun 13 13:43:34 2019 -0700
+++ b/make/autoconf/bootcycle-spec.gmk.in    Wed Jun 19 10:01:31 2019 -0700
@@ -62,3 +62,5 @@
  endif
  # The bootcycle JVM arguments may differ from the original boot jdk.
  JAVA_FLAGS_BIG := @BOOTCYCLE_JVM_ARGS_BIG@
+# The bootcycle JVM cannot use the configure-support/classes.jsa 
generated by the original boot jdk.
+JAVA_FLAGS += -Xshare:off


We could try to fix the bootcycle build to use the proper classes.jsa, 
but I am
not sure if enough people use it to worth the effort.


Thanks
- Ioi