Added stricter error checks by the compiler, and adapted all impacted code.

Primarily -
* Added "static" to static functions.
* Added proper signature with "void" to functions without arguments.
* Marked unused arguments with "(void)".
* Removed entirely unused static functions.
* Added "const" to preserve const-correctness.
* Added function prototypes for external functions.

extras/fixture/src/unity_fixture_malloc_overrides.h

@@ -13,4 +13,9 @@
 #define realloc unity_realloc
 #define free    unity_free
 
+void* unity_malloc(size_t size);
+void* unity_calloc(size_t num, size_t size);
+void* unity_realloc(void * oldMem, size_t size);
+void unity_free(void * mem);
+
 #endif /* UNITY_FIXTURE_MALLOC_OVERRIDES_H_ */