Fixes in eval, Rf_eval and implement R_tryEval

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

...l/src/com/oracle/truffle/r/ffi/impl/nodes/RfEvalNode.java

...rc/com/oracle/truffle/r/ffi/impl/nodes/TryRfEvalNode.java

...com/oracle/truffle/r/ffi/impl/upcalls/StdUpCallsRFFI.java

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

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

...me/src/com/oracle/truffle/r/runtime/VirtualEvalFrame.java

...time/src/com/oracle/truffle/r/runtime/context/Engine.java

...est.native/packages/testrffi/testrffi/tests/simpleTests.R

...est/src/com/oracle/truffle/r/test/ExpectedTestOutput.test

.../com/oracle/truffle/r/test/builtins/TestBuiltin_eval.java