[GR-2798] Fixes in restart handlers and other smaller fixes.

...fle.r.engine/src/com/oracle/truffle/r/engine/REngine.java

...library/src/com/oracle/truffle/r/library/stats/PPSum.java

...n/src/com/oracle/truffle/r/nodes/builtin/base/CharTr.java

...acle/truffle/r/nodes/builtin/base/ConditionFunctions.java

...in/src/com/oracle/truffle/r/nodes/builtin/base/Round.java

...e.r.runtime/src/com/oracle/truffle/r/runtime/RCaller.java

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

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

...com/oracle/truffle/r/test/builtins/TestBuiltin_round.java

...le/truffle/r/test/library/base/TestConditionHandling.java