Miscellaneous LLVM-related fixes

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

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

...m/oracle/truffle/r/ffi/impl/llvm/TruffleLLVM_Context.java

...r/ffi/impl/llvm/upcalls/BytesToNativeCharArrayCallMR.java

.../com/oracle/truffle/r/ffi/impl/nodes/DoMakeClassNode.java

.../com/oracle/truffle/r/ffi/impl/nodes/GetClassDefNode.java

...oracle/truffle/r/ffi/impl/nodes/NativeStringCastNode.java

...cle/truffle/r/ffi/impl/nodes/NewCustomConnectionNode.java

...src/com/oracle/truffle/r/ffi/impl/nodes/Str2TypeNode.java

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

...oracle.truffle.r.native/fficall/src/truffle_llvm/Memory.c

com.oracle.truffle.r.native/llvm_tools/llvm-ar

com.oracle.truffle.r.native/llvm_tools/llvm-c++

com.oracle.truffle.r.native/llvm_tools/llvm-cc

com.oracle.truffle.r.native/llvm_tools/llvm-fc

com.oracle.truffle.r.native/llvm_tools/llvm-helper

...src/com/oracle/truffle/r/runtime/data/CharSXPWrapper.java

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

...untime/src/com/oracle/truffle/r/runtime/data/RObject.java

.../src/com/oracle/truffle/r/test/generate/FastRSession.java