Introduce transitional API for CForLoop to migrate off BlockStmt::blockInfoGet/Set
Update internal uses of blockInfoGet/Set to specify the BlockStmt implementation
Convert implicits calls to CForLoop::blockInfoGet/Set to transitional CForLoop::cforInfoGet/Set
Merge pull request #935 from noakesmichael/cforLoop

Transition away from blockInfoGet/Set for CForLoop

1) Introduce a transitional API for CForLoop to migrate off BlockStmt::blockInfoGet/Set

2) Update internal uses of BlockStmt::blockInfoGet/Set

3) Update external uses of BlockStmt::blockInfoGet/Set

Compiled: STD clang/darwin, STD gcc/linux64, LLVM gcc/linux64
Tested: paratest --verify
Review: none