[8u20] RFR Backport of JDK-8041918: BootstrapMethods attribute cannot be empty

[Lois Foltan]

Please approve the backport of JDK-8041918 to jdk8u.  The changeset 
applied cleanly.

The bug:
https://bugs.openjdk.java.net/browse/JDK-8041918

The webrev:
http://cr.openjdk.java.net/~lfoltan/bug_jdk8041918_8u/

The JDK 9 changeset:
http://hg.openjdk.java.net/jdk9/hs-rt/hotspot/rev/cb82a30966ac

Thanks,
Lois