Fix VarArgs tests on arm64

Arm64 calling convention requires varargs to always be passed on the stack. JNA's and ffi's argument handling logic seems to handle this case correctly, but it is important that the Java definitions match their native counterparts exactly.

test/com/sun/jna/VarArgsTest.java

@@ -42,8 +42,8 @@ protected List<String> getFieldOrder() {
         }
         public int addVarArgs(String fmt, Number... args);
         public String returnStringVarArgs(String fmt, Object... args);
-        public void modifyStructureVarArgs(String fmt, Object arg1, Object... args);
-        public String returnStringVarArgs2(String... args);
+        public void modifyStructureVarArgs(String fmt, Object... args);
+        public String returnStringVarArgs2(String fmt, String... args);
     }
     TestLibrary lib;
     @Override