ext_vector IRGen. Patch to allow indexing into 
ext_vector_type's 'hi/lo' components when
used as lvalue. rdar://18031917 pr20697


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@215991 91177308-0d34-0410-b5e6-96231b3b80d8
Add tests for coverage mapping generation.

This patch adds the tests for the coverage mapping generation. 
Most of the tests check the mapping regions produced by 
the generator, and one checks the llvm IR.

Differential Revision: http://reviews.llvm.org/D4847


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@215995 91177308-0d34-0410-b5e6-96231b3b80d8