Bug fix for customer patch for final QA leading up to their release. This commit incorporates r7216 which is a bug fix for a ConcurrentModificationException in the ASTComplexOptionalOptimizer.

I have applied that one bug fix to the 1.2.3 maintenance branch: branches/BIGDATA_RELEASE_1_2_3/.  That branch r7185. Due to a goof in the release process, tags/BIGDATA_RELEASE_1_2_3/ is r7188. However, both r7185 and r7188 are for exactly the same SVN commit point, which is r7184.

See https://sourceforge.net/apps/trac/bigdata/ticket/777 (ConcurrentModificationException in ASTComplexOptionalOptimizer)

git-svn-id: https://bigdata.svn.sourceforge.net/svnroot/bigdata/branches/BIGDATA_RELEASE_1_2_3@7564 8f7bc0f5-282e-0410-95e3-8d296e9bb460