Merge pull request #4696 from oranagra/zrealloc_fix

Fix zrealloc to behave similarly to je_realloc when size is 0

src/zmalloc.c

@@ -148,6 +148,10 @@ void *zrealloc(void *ptr, size_t size) {
     size_t oldsize;
     void *newptr;
 
+    if (size == 0 && ptr!=NULL) {
+        zfree(ptr);
+        return NULL;
+    }
     if (ptr == NULL) return zmalloc(size);
 #ifdef HAVE_MALLOC_SIZE
     oldsize = zmalloc_size(ptr);