RFFI tests added for new upcalls

...src/com/oracle/truffle/r/ffi/codegen/FFITestsCodeGen.java

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

...om/oracle/truffle/r/ffi/impl/nodes/RForceAndCallNode.java

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

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

...e.truffle.r.native/fficall/src/common/rffi_upcallsindex.h

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

....truffle.r.test.native/packages/testrffi/testrffi/R/api.R

...fle.r.test.native/packages/testrffi/testrffi/R/testrffi.R

...uffle.r.test.native/packages/testrffi/testrffi/src/init.c

...e.r.test.native/packages/testrffi/testrffi/src/init_api.h

...test.native/packages/testrffi/testrffi/src/rffiwrappers.c

...test.native/packages/testrffi/testrffi/src/rffiwrappers.h

...e.r.test.native/packages/testrffi/testrffi/src/testrffi.c

...e.r.test.native/packages/testrffi/testrffi/src/testrffi.h

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