Restore arm's machine/endian.h to be useful for ARMv5

Revert bionic c54ca40aef48009e7b0e5b2b3069aad62ffd3453 because
endian.h is seen by APP_ABI=armeabi as well.  Instruction
"rev" and "rev16" doesn't exist until ARMv6

Change-Id: I653740e3704b9b64e3e2a2e17452675635a14776
1 file changed