[libc++] Remove non-existent headers from header_information.py

experimental/algorithm and experimental/functional no longer exist, but header_information.py still has references.

Differential Revision: https://reviews.llvm.org/D157639

Author: ian-twilightcoder

libcxx/utils/libcxx/test/header_information.py

@@ -15,10 +15,8 @@
     "coroutine": "// UNSUPPORTED: c++03, c++11, c++14, c++17",
     "cwchar": "// UNSUPPORTED: no-wide-characters",
     "cwctype": "// UNSUPPORTED: no-wide-characters",
-    "experimental/algorithm": "// UNSUPPORTED: c++03",
     "experimental/deque": "// UNSUPPORTED: c++03",
     "experimental/forward_list": "// UNSUPPORTED: c++03",
-    "experimental/functional": "// UNSUPPORTED: c++03",
     "experimental/iterator": "// UNSUPPORTED: c++03",
     "experimental/list": "// UNSUPPORTED: c++03",
     "experimental/map": "// UNSUPPORTED: c++03",