* sysdeps/unix/sysv/linux/mips/mips64/n32/truncate64.c: New.
* sysdeps/unix/sysv/linux/kernel-features.h: fcntl64 is available
on mips n32.
* sysdeps/unix/sysv/linux/mips/kernel_stat.h: Explain why
XSTAT_IS_XSTAT64 must not be used for mips n64. Use 64-bit data
structure on n32 as well.
* sysdeps/unix/sysv/linux/mips/bits/stat.h: Use POSIX-compliant
data types on n32 and n64.
