* mips-opc.c (mips_builtin_opcodes): Add "sync_acquire",
"sync_mb", "sync_release", "sync_rmb" and "sync_wmb".
gas/testsuite/
* gas/mips/mips32r2-sync.d: New test for MIPS32r2 "sync"
instruction variants.
* gas/mips/octeon@mips32r2-sync.d: Likewise, Octeon version.
* gas/mips/mips32r2-sync.s: Source for the new test.
* gas/mips/mips.exp: Run the new test.