A container of const T uses std::allocator<const T>, which was an
undocumented libc++ extension that has been removed.
See https://github.com/llvm/llvm-project/pull/96319.
Bug: 349681543
Test: m libstagefright_aidl_bufferpool2
Change-Id: I6491377d6275c5d18cd91b40184d6f05cff7cb9a
Currently same connection id can be given to different connections if
they don't belong to the same bufferpool.
Ensure uniqueness of connection id for each connection.
Bug: 323793249
Change-Id: I350872e6d60736ea4525d473944c92b5fe3f5f84