Adding conjugate function.

Author: ppisl

graalpython/com.oracle.graal.python.test/src/tests/unittest_tags/test_complex.txt

@@ -1,5 +1,6 @@
 *ComplexTest.test_abs
 *ComplexTest.test_boolcontext
+*ComplexTest.test_conjugate
 *ComplexTest.test_divmod
 *ComplexTest.test_file
 *ComplexTest.test_getnewargs

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/complex/ComplexBuiltins.java

@@ -632,4 +632,13 @@ int hash(PComplex self) {
             return realHash + PComplex.IMAG_MULTIPLIER * imagHash;
         }
     }
+    
+    @GenerateNodeFactory
+    @Builtin(name = "conjugate", minNumOfPositionalArgs = 1)
+    abstract static class ConjugateNode extends PythonUnaryBuiltinNode {
+        @Specialization
+        PComplex hash(PComplex self) {
+            return factory().createComplex(self.getReal(), -self.getImag());
+        }
+    }
 }