downloads: upgrade libffi to 3.3

Author: indygreg

pythonbuild/downloads.py

@@ -130,10 +130,10 @@
         "license_file": "LICENSE.libedit.txt",
     },
     "libffi": {
-        "url": "ftp://sourceware.org/pub/libffi/libffi-3.2.1.tar.gz",
-        "size": 940837,
-        "sha256": "d06ebb8e1d9a22d19e38d63fdb83954253f39bedc5d46232a05645685722ca37",
-        "version": "3.2.1",
+        "url": "ftp://sourceware.org/pub/libffi/libffi-3.3.tar.gz",
+        "size": 1305466,
+        "sha256": "72fba7922703ddfa7a028d513ac15a85c8d54c8d67f55fa5a4802885dc652056",
+        "version": "3.3",
         "library_names": ["ffi"],
         "licenses": ["MIT"],
         "license_file": "LICENSE.libffi.txt",