Request for phase 2 approval for CR 7102515 - javac running very very long and not returning

[Jim Holmlund]

The bug:
	http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7102515

The changeset is the same as in JDK 8:
         http://hg.openjdk.java.net/jdk8/tl/langtools/rev/366c233eb838

The target repo:
	http://hg.openjdk.java.net/jdk7u/jdk7u2-dev-gate/langtools/

This is a regression from JDK 6 that occurs when several string concatenate operators are used in an 
expression.  This causes the build of the deploy repo to fail.

Risks:
	No special risks, other than the usual risks associated with a change.
	The change is two parts:
	- empty the cache as is done for the other similar operators but which
	  was omitted from the code for the resolveOperator method
         - change the code so that a simple error message is produced instead of doing the advanced
	  analysis that caused the problem.

Testing:
- langtools regression tests pass as expected
- JCK-Compiler-7 tests pass as expected
- This change was pushed to jdk8/tl/langtools on Oct 19.
   It has been thru the nightly test of Oct 19 with no failures
	http://aurora-ds.ru.oracle.com:13000/functional/faces/ChessBoard.xhtml?reportName=J2SESQELangToolsNightly&parameters=[release]1.8.0[nightlyDate]%24{lastNightlyDate}[component]jck-compiler%2Cregression%2Flangtools%2Ctools&splitting=[X+axis]os[Complement]tags%2C+buildType%2C+productConfiguration%2C+VMMode%2C+VMFlavor%2C+hostname%2C+harness%2C+osFlavor%2C+osVersion%2C+date%2C+baseline%2C+batch%2C+testsuite%2C+bitness[Y+axis]component%2C+build%2C+vmbuild[Z+axis]release%2C+vmrelease&reference=[Others]release%2C+build%2C+vmrelease%2C+vmbuild%2C+tags%2C+buildType%2C+bitness%2C+productConfiguration%2C+VMMode%2C+VMFlavor%2C+hostname%2C+harness%2C+os%2C+osFlavor%2C+date%2C+baseline%2C+batch%2C+testsuite%2C+component[Reference+Set]&mixReference=false&flags=Show+Passed%2C+Show+Pass+Rate%2C+Show+Known%2C+Show+Unknown&significance=empty&hideDataConfiguration=true&calculateSummary=true&showComplementAttributes=false&compactTables=true&viewStyle=chessboard&filter=


Author:   Maurizio Cimadamore
Reviewed by:  Jon Gibbons, Jim Holmlund