[GR-2708] Modifications in FastR to be able to install and run package "testthat".

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

...rc/com/oracle/truffle/r/engine/RRuntimeASTAccessImpl.java

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

...le.truffle.r.native/fficall/src/truffle_llvm/Rinternals.c

...n/src/com/oracle/truffle/r/nodes/builtin/base/IsATTY.java

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

...fle.r.nodes/src/com/oracle/truffle/r/nodes/RASTUtils.java

...c/com/oracle/truffle/r/nodes/ffi/JavaUpCallsRFFIImpl.java

...s/src/com/oracle/truffle/r/nodes/ffi/UpCallsRFFIImpl.java

...rc/com/oracle/truffle/r/runtime/conn/FileConnections.java

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

...est/src/com/oracle/truffle/r/test/ExpectedTestOutput.test

...le/truffle/r/test/library/base/TestConditionHandling.java

...le/r/test/library/base/condition/R/withCallingHandlers0.R

...le/r/test/library/base/condition/R/withCallingHandlers1.R