[GR-2798] Implement 'influence' external from stats package.

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

...racle/truffle/r/ffi/impl/managed/Managed_RFFIFactory.java

...c/com/oracle/truffle/r/ffi/impl/nfi/TruffleNFI_Stats.java

...ary/src/com/oracle/truffle/r/library/stats/Influence.java

...le.r.native/gnur/patch/src/library/stats/src/stats_rffi.c

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

.../nodes/builtin/base/foreign/CallAndExternalFunctions.java

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

...ntime/src/com/oracle/truffle/r/runtime/ffi/StatsRFFI.java

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

.../truffle/r/test/library/stats/TestExternal_influence.java

mx.fastr/copyrights/overrides