This patch consolidates mostly of the Linux posix_fadvise{64} implementations
on sysdeps/unix/sysv/linux/posix_fadvise{64}.c. It still keeps arch-specific
files for:
* S390-32: it uses a packed structure to pass all the arguments on syscall.
It is the only supported port that implements __NR_fadvise64_64 in this
way.
* ARM: it does not implement __NR_fadvise64 (as other 32-bits ports), so
posix_fadvise calls internal posix_fadvise64 symbol.
* MIPS64 n64: it requires a different version number that other ports.
The new macro SYSCALL_LL{64} is used to handle the offset argument and
INTERNAL_SYSCALL_CALL to handle passing the correct number of expect
arguments.
The default Linux adds two new defines a port can use to control how
__NR_fadvise64_64 passes the kernel arguments:
* __ASSUME_FADVISE64_64_6ARG: the 'advise' argument is moved on second
position. This is the case of powerpc32 and arm to avoid implement
7 argument syscall.
* __ASSUME_FADVISE64_64_NO_ALIGN: for ABIs that defines
__ASSUME_ALIGNED_REGISTER_PAIRS packs the offset without the leading
'0'. This is the case of tile 32 bits.
ARM also defines __NR_fadvise64_64 as __NR_arm_fadvise64_64 (which is also
handled on arch kernel-feature.h).