Avoid -Wempty-body warnings from SWIG_contract_assert

Examples/test-suite/aggregate.i

@@ -6,7 +6,7 @@
    To support contracts, you need to add a macro to the runtime.
    For Python, it looks like this:
 
-#define SWIG_contract_assert(expr, msg)  if (!(expr)) { PyErr_SetString(PyExc_RuntimeError, (char *) msg #expr ); goto fail; } else
+#define SWIG_contract_assert(expr, msg)  do { if (!(expr)) { PyErr_SetString(PyExc_RuntimeError, (char *) msg #expr ); goto fail; } } while (0)
 
    Note: It is used like this:
    SWIG_contract_assert(x == 1, "Some kind of error message");

Examples/test-suite/javascript/Makefile.in

@@ -47,9 +47,6 @@ ifeq (node,$(JSENGINE))
   SWIGOPT += -v8 -DBUILDING_NODE_EXTENSION=1
 
   # shut up some warnings
-  # contract macro has an empty 'else' at the end...
-  aggregate.cpptest: GYP_CFLAGS = \"-Wno-empty-body\"
-  contract.cpptest: GYP_CFLAGS = \"-Wno-empty-body\"
 
   # dunno... ignoring generously
   apply_signed_char.cpptest: GYP_CFLAGS = \"-Wno-ignored-qualifiers\"