[GR-8167] Issues in match.arg builtin.

...src/com/oracle/truffle/r/nodes/builtin/base/MatchArg.java

...rc/com/oracle/truffle/r/nodes/builtin/base/Transpose.java

...runtime/src/com/oracle/truffle/r/runtime/Collections.java

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

.../oracle/truffle/r/test/builtins/TestBuiltin_matcharg.java

...src/com/oracle/truffle/r/test/builtins/TestBuiltin_t.java

...om/oracle/truffle/r/test/builtins/TestBuiltin_unique.java