[StaticAnalyzer] Handle LoopExit CFGElement in the analyzer
[StaticAnalyzer] Handle LoopExit CFGElement in the analyzer

This patch adds handling of the LoopExit CFGElements to the StaticAnalyzer.
This is reached by introducing a new ProgramPoint.
Tests will be added in a following commit.

Differential Revision: https://reviews.llvm.org/D35670


git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@311344 91177308-0d34-0410-b5e6-96231b3b80d8

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