Emulate cooperativeness of GNUR's GC

...c/com/oracle/truffle/r/ffi/impl/common/Generic_Tools.java

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

.../com/oracle/truffle/r/ffi/impl/llvm/TruffleLLVM_Call.java

.../oracle/truffle/r/ffi/impl/upcalls/MemoryUpCallsRFFI.java

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

.../src/com/oracle/truffle/r/ffi/processor/FFIProcessor.java

...ssor/src/com/oracle/truffle/r/ffi/processor/RFFINoGC.java

.../nodes/builtin/base/foreign/CallAndExternalFunctions.java

...me/src/com/oracle/truffle/r/runtime/context/RContext.java

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

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

...untime/src/com/oracle/truffle/r/runtime/ffi/CallRFFI.java

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