Revert "Cleanup: remove declaration for removed function"

This reverts commit aa363ec2ae.

The function still exists, this commit caused a warning with Clang
So keep MEM_printmemlist_pydict.

intern/guardedalloc/MEM_guardedalloc.h

@@ -147,6 +147,12 @@ extern void *(*MEM_mallocN_aligned)(size_t len,
                                     const char *str) /* ATTR_MALLOC */ ATTR_WARN_UNUSED_RESULT
     ATTR_ALLOC_SIZE(1) ATTR_NONNULL(3);
 
+/**
+ * Print a list of the names and sizes of all allocated memory
+ * blocks. as a python dict for easy investigation.
+ */
+extern void (*MEM_printmemlist_pydict)(void);
+
 /**
  * Print a list of the names and sizes of all allocated memory blocks.
  */