[GR-2738] Do not use “null” source sections.

...ine/src/com/oracle/truffle/r/engine/TruffleRLanguage.java

...ruffle/r/engine/interop/RAbstractVectorAccessFactory.java

...om/oracle/truffle/r/ffi/impl/nodes/FFIUpCallRootNode.java

...ruffle/r/nodes/builtin/base/printer/ValuePrinterNode.java

...st/src/com/oracle/truffle/r/nodes/test/TestUtilities.java

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

...me/src/com/oracle/truffle/r/runtime/ffi/RFFIRootNode.java

...me/src/com/oracle/truffle/r/runtime/rng/user/UserRNG.java