Cherry pick bionic 86d2feef9f4df517dd5755b39b993bec0c3e1ea5 which
fixes struct stat64. This may look like breaking mips64 ABI, but mips64
support is stil work in progress post-L
Also see prebuilts/ndk e6639a4c0ba9296a19fd477154aace3585221d9d
Change-Id: Ia8859762191220b9d3127b37970f05594375ca40
1. move sgidefs.h to libc/arch-mips.
See bionic 6e50cb454451916ced315680f6c13dc08cf3959a
2. change type of u_ar0 from "unsigned long" to "struct user_regs_struct*".
See bionic e03950fa0c5567edf70d011b856a027e03b1c0f7
3. sync fts.h, dlext.h, sys/user.h
4. remove ' from string.h
Change-Id: I2ba58b0df4c655f107ea086efbd0220de2b40e9a