test-skeleton: Support 2 comm pipes between TEST_FORK child and parent.
test-skeleton: Support 2 comm pipes between TEST_FORK child and parent.

These pipes are accessible via TEST_FORK_PING_* and TEST_FORK_WAIT_*
macros and allow to synchronize between the child and the parend by
waiting on each other's signals.

bitwiseworks/libcx,bitwiseworks/libcx