Fix style

Author: Pavel Marek

com.oracle.truffle.r.nodes.builtin/src/com/oracle/truffle/r/nodes/builtin/base/foreign/CallAndExternalFunctions.java

@@ -32,7 +32,6 @@
 import com.oracle.truffle.api.CompilerDirectives;
 import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
-import com.oracle.truffle.api.TruffleLanguage.ContextReference;
 import com.oracle.truffle.api.dsl.Cached;
 import com.oracle.truffle.api.dsl.Fallback;
 import com.oracle.truffle.api.dsl.Specialization;
@@ -104,8 +103,6 @@
 import com.oracle.truffle.r.runtime.builtins.RBehavior;
 import com.oracle.truffle.r.runtime.builtins.RBuiltin;
 import com.oracle.truffle.r.runtime.builtins.RBuiltinKind;
-import com.oracle.truffle.r.runtime.context.RContext;
-import com.oracle.truffle.r.runtime.context.TruffleRLanguage;
 import com.oracle.truffle.r.runtime.data.RArgsValuesAndNames;
 import com.oracle.truffle.r.runtime.data.RDataFactory;
 import com.oracle.truffle.r.runtime.data.RExternalPtr;