Merge branch 'PHP-5.6' into PHP-7.1

Merge branch 'PHP-5.6' into PHP-7.1

* PHP-5.6:
  Fix bug #77418 - Heap overflow in utf32be_mbc_to_code
  [ci skip] Add NEWS
  Fix more issues with encodilng length
  Fix #77270: imagecolormatch Out Of Bounds Write on Heap
  Fix bug #77380  (Global out of bounds read in xmlrpc base64 code)
  Fix bug #77371 (heap buffer overflow in mb regex functions - compile_string_node)
  Fix bug #77370 - check that we do not read past buffer end when parsing multibytes
  Fix #77269: Potential unsigned underflow in gdImageScale
  Fix bug #77247 (heap buffer overflow in phar_detect_phar_fname_ext)
  Fix bug #77242 (heap out of bounds read in xmlrpc_decode())
  Regenerate certs for openssl tests