glibc gives the `struct ipc64_perm` fields `key` and `seq` double-underscore
names. strace refers to the fields by those names, and there's no obvious
reason not to go along with this.
Bug: N/A
Test: built strace 4.15 with a hacked NDK
Change-Id: I8b2b0f75363349d99edaecda50fe897ee0fa0c65
Also fix <sys/ipc.h>.
Not useful except to systems/bringup folks for testing. Trivial tests
added, and double-checked under strace to see that things look right.
x86 -- which works differently to everything else -- tested on the host.
Bug: http://b/27952303
Change-Id: I328534e994ae9e90755f545478fba03038c0bb94
