[GR-2527] Fix signature of R_NewHashedEnv, NFI Cstring signatures.

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

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

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

.../src/com/oracle/truffle/r/nodes/ffi/RFFIUpCallMethod.java

...om/oracle/truffle/r/nodes/ffi/TracingUpCallsRFFIImpl.java

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

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

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

...oracle/truffle/r/test/tools/RFFIUpCallMethodGenerate.java