[GR-6518] Native symbols exported by FastR's libraries are the same as GNUR's.

...fle.r.engine/src/com/oracle/truffle/r/engine/REngine.java

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

...com/oracle/truffle/r/ffi/impl/nfi/TruffleNFI_Context.java

...truffle.r.native/fficall/src/common/rffi_variablesindex.h

...acle.truffle.r.native/fficall/src/truffle_nfi/variables.c

com.oracle.truffle.r.native/version.source

...om/oracle/truffle/r/nodes/builtin/fastr/FastRInterop.java

...ime/src/com/oracle/truffle/r/runtime/ffi/RFFIContext.java

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

mx.fastr/mx_fastr_edinclude.py