bpo-36459: Fix a possible double PyMem_FREE() due to tokenizer.c's tok_nextc() (12601)

Remove the PyMem_FREE() call added in cb90c89. The buffer will be freed when PyTokenizer_Free() is called on the tokenizer state. (cherry picked from commit cda139d) Co-authored-by: Zackery Spytz <zspytz@gmail.com>

Author: miss-islington

Misc/NEWS.d/next/Core and Builtins/2019-03-27-22-35-16.bpo-36459.UAvkKp.rst

@@ -0,0 +1 @@
+Fix a possible double ``PyMem_FREE()`` due to tokenizer.c's ``tok_nextc()``.

Parser/tokenizer.c

@@ -1055,7 +1055,6 @@ tok_nextc(struct tok_state *tok)
  newbuf = (char *)PyMem_REALLOC(newbuf,
  newsize);
  if (newbuf == NULL) {
- PyMem_FREE(tok->buf);
  tok->done = E_NOMEM;
  tok->cur = tok->inp;
  return EOF;