[GR-137] Cast pipelines in some external Builtins.

...om/oracle/truffle/r/library/methods/SubstituteDirect.java

...c/com/oracle/truffle/r/library/stats/SplineFunctions.java

...y/src/com/oracle/truffle/r/library/utils/TypeConvert.java

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

...om/oracle/truffle/r/nodes/builtin/base/foreign/Dqrcf.java

...le/r/nodes/builtin/base/foreign/FortranAndCFunctions.java

...src/com/oracle/truffle/r/nodes/builtin/RList2EnvNode.java

...le.r.runtime/src/com/oracle/truffle/r/runtime/RError.java

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

...racle/truffle/r/test/builtins/TestBuiltin_substitute.java

.../truffle/r/test/library/methods/TestSubstituteDirect.java

...cle/truffle/r/test/library/stats/TestSplineFunctions.java

.../oracle/truffle/r/test/library/utils/TestTypeConvert.java

mx.fastr/mx_fastr.py