RFFI implementation to support digest package

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

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

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

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

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

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

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

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

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

com.oracle.truffle.r.native/fficall/jni/src/rffiutils.h

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

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

...oracle/truffle/r/nodes/builtin/base/DynLoadFunctions.java

...truffle/r/nodes/builtin/base/HiddenInternalFunctions.java

...racle/truffle/r/nodes/builtin/base/PrettyPrinterNode.java

...acle/truffle/r/nodes/builtin/base/SerializeFunctions.java

.../com/oracle/truffle/r/runtime/ffi/jnr/CallRFFIHelper.java

...com/oracle/truffle/r/runtime/ffi/jnr/CallRFFIWithJNI.java

....runtime/src/com/oracle/truffle/r/runtime/RSerialize.java

.../com/oracle/truffle/r/runtime/conn/ConnectionSupport.java