[GR-5333] Add Rf_str2type and simulate DllInfo layout.

...oracle/truffle/r/ffi/impl/common/JavaUpCallsRFFIImpl.java

...acle/truffle/r/ffi/impl/llvm/TruffleLLVM_RFFIFactory.java

...oracle.truffle.r.native/fficall/src/common/rffi_upcalls.h

...ve/fficall/src/truffle_common/Rinternals_truffle_common.h

com.oracle.truffle.r.native/version.source

...tin/src/com/oracle/truffle/r/nodes/builtin/base/Slot.java

...c/com/oracle/truffle/r/runtime/data/NativeDataAccess.java

...r.runtime/src/com/oracle/truffle/r/runtime/ffi/CRFFI.java

...e.r.runtime/src/com/oracle/truffle/r/runtime/ffi/DLL.java