Stats: port nbinom distribution

...brary/src/com/oracle/truffle/r/library/stats/DNBinom.java

...brary/src/com/oracle/truffle/r/library/stats/PNBinom.java

...brary/src/com/oracle/truffle/r/library/stats/QNBinom.java

...brary/src/com/oracle/truffle/r/library/stats/RNBinom.java

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

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

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

...racle/truffle/r/test/library/stats/TestDistributions.java

...le/truffle/r/test/library/stats/TestExternal_rnbinom.java

...fle/r/test/library/stats/TestRandGenerationFunctions.java

mx.fastr/copyrights/overrides

testScript.R