(llvm3.5) Start the llvm3.5 branch

Force c++11 compilation under unix platforms
Fix issues with linker options & compile definitions
Improve CMake traces
(llvm3.5) Update headers inclusion

Support/PassNameParser.h ->  IR/LegacyPassNameParser.h
Analysis/Verifier.h      ->  IR/Verifier.h
(llvm3.5) Use proper c++11 loops to get users for a variable
(llvm3.5) DataLayout is not a Pass anymore

It must be replaced by DataLayoutPass
(llvm3.5) Finish the 3.4 -> 3.5 migration
(cmake) Clean useless LLVM components to link against