Converting varargs to pairlist if used with CAR/CDR.

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

...cle/truffle/r/ffi/impl/common/TracingUpCallsRFFIImpl.java

.../com/oracle/truffle/r/ffi/impl/nodes/ListAccessNodes.java

...pl/src/com/oracle/truffle/r/ffi/impl/nodes/MiscNodes.java

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

...racle.truffle.r.native/fficall/src/common/inlined_fastr.c

com.oracle.truffle.r.native/fficall/src/jni/Rinternals.c

...odes/builtin/base/printer/RArgsValuesAndNamesPrinter.java

...e/truffle/r/nodes/builtin/base/printer/ValuePrinters.java

...om/oracle/truffle/r/runtime/data/RArgsValuesAndNames.java

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

...oracle/truffle/r/test/builtins/TestBuiltin_serialize.java