libcutils: sockets_test breaks MAC build

- Neuter SOCK_NONBLOCK and SOCK_CLOEXEC if they are not defined.
- F_SETFL O_NONBLOCK after socket() call.
- Correct environment reference (we recently changed handler to
  replace non-ascii and non-numericals with '_' for env tag).

Test: libcutils_test32 --gtest_filter=SocketsTest.android_get_control_socket
Bug: 32450474
Change-Id: I409a8c2c78e5f057af5fd6251cbd8657018be22b