file functions fixes when setwd called; re-implement Sys.glob using OS native function

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

...om/oracle/truffle/r/nodes/builtin/base/FileFunctions.java

...om/oracle/truffle/r/nodes/builtin/base/NormalizePath.java

...c/com/oracle/truffle/r/nodes/builtin/base/PathExpand.java

...com/oracle/truffle/r/nodes/builtin/base/SysFunctions.java

...m/oracle/truffle/r/runtime/ffi/gnfi/GNFI_RFFIFactory.java

...ffi/src/com/oracle/truffle/r/runtime/ffi/jnr/JNIGlob.java

...com/oracle/truffle/r/runtime/ffi/jnr/JNR_RFFIFactory.java

...untime/src/com/oracle/truffle/r/runtime/ffi/BaseRFFI.java