More standard conforming codec_realloc()

- Leave original ptr untouched if allocation fails
  (bail out early)
- Behave like malloc() in case ptr is NULL

Change-Id: Ib854ca19bd0e069999b7780d2d9a533ece705add

lib/rbcodec/codecs/lib/codeclib.c

@@ -91,8 +91,12 @@ void* codec_realloc(void* ptr, size_t size)
 {
     void* x;
     x = codec_malloc(size);
-    ci->memcpy(x, ptr, size);
-    codec_free(ptr);
+    if (x == NULL)
+        return NULL;
+    if (ptr) {
+        ci->memcpy(x, ptr, size);
+        codec_free(ptr);
+    }
     return(x);
 }