[GR-136] Additional changes for LLVM support.

.../src/com/oracle/truffle/r/engine/interop/RFunctionMR.java

.../src/com/oracle/truffle/r/engine/interop/RLanguageMR.java

...ne/src/com/oracle/truffle/r/engine/interop/RSymbolMR.java

...com/oracle/truffle/r/ffi/impl/common/Generic_PkgInit.java

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

.../com/oracle/truffle/r/ffi/impl/common/PkgInitUpCalls.java

...l/src/com/oracle/truffle/r/ffi/impl/common/RFFIUtils.java

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

...rc/com/oracle/truffle/r/ffi/impl/common/UpCallUnwrap.java

.../com/oracle/truffle/r/ffi/impl/interop/NativePointer.java

.../oracle/truffle/r/ffi/impl/interop/base/GlobResultMR.java

...cle/truffle/r/ffi/impl/interop/base/ReadlinkResultMR.java

...racle/truffle/r/ffi/impl/interop/base/StrtolResultMR.java

...oracle/truffle/r/ffi/impl/interop/base/UnameResultMR.java

...truffle/r/ffi/impl/interop/pcre/CaptureNamesResultMR.java

...acle/truffle/r/ffi/impl/interop/pcre/CompileResultMR.java

.../truffle/r/ffi/impl/interop/pkginit/ForceSymbolsCall.java

...ruffle/r/ffi/impl/interop/pkginit/ForceSymbolsCallMR.java

.../truffle/r/ffi/impl/interop/pkginit/GetCCallableCall.java

...ruffle/r/ffi/impl/interop/pkginit/GetCCallableCallMR.java