Add configuration option UNITY_EXCLUDE_STDLIB_MALLOC to Fixture

This feature removes the dependency on malloc/free for constrained
  embedded systems without a heap. It uses a static heap inside
  Unity Fixture. Setting UNITY_INTERNAL_HEAP_SIZE_BYTES sizes the heap.
 Add tests for new option, add targets to makefile for running tests.
 UNITY_FIXTURE_MALLOC for Fixture use only, remove from unity_output_Spy.c.

extras/fixture/test/main/AllTests.c

@@ -11,7 +11,8 @@ static void runAllTests(void)
 {
     RUN_TEST_GROUP(UnityFixture);
     RUN_TEST_GROUP(UnityCommandOptions);
-    RUN_TEST_GROUP(LeakDetection)
+    RUN_TEST_GROUP(LeakDetection);
+    RUN_TEST_GROUP(InternalMalloc);
 }
 
 int main(int argc, const char* argv[])