Remove __ASSUME_ST_INO_64_BIT.

Remove __ASSUME_ST_INO_64_BIT.

kernel-features.h has a macro __ASSUME_ST_INO_64_BIT, with a comment
"However, SH is lame, and still does not have a 64-bit inode field.".

The macro is, in fact, defined to 0 by Alpha as well as SH.  The Alpha
case is, however, trivially useless: none of the files that test
__ASSUME_ST_INO_64_BIT are built for Alpha (which gained kernel
support for stat64 syscalls, with a 64-bit st_ino field, in Linux
2.6.4; the define to 0 for Alpha in glibc predates that).

The SH kernel gained support for a 64-bit st_ino in struct stat64 in
commit 760bcb1deec13c50e20399c84cb6a8ea41cc2820 ("sh: Fix fstatat64()
syscall."), which is in Linux 2.6.22 and later.  So the redefinition
of __ASSUME_ST_INO_64_BIT to 0 is of no use for SH either; three of
the files testing it do so immediately after a stat64-family syscall
has been used, which will always have set the 64-bit st_ino correctly
(in addition to the 32-bit __st_ino), while the relevant code
__xstat32_conv executes only after such a syscall in the function
calling __xstat32_conv.

Thus this patch removes __ASSUME_ST_INO_64_BIT and code testing it.
Removing the useless [!__ASSUME_ST_INO_64_BIT] code in __xstat32_conv
renders the [_HAVE_STAT64___ST_INO] and [!_HAVE_STAT64___ST_INO] cases
around it identical, so that conditional is also removed.

Tested compilation with build-many-glibcs.py for its Alpha and SH
configurations; also ran the glibc testsuite for x86_64 and x86.

	* sysdeps/unix/sysv/linux/kernel-features.h
	(__ASSUME_ST_INO_64_BIT): Remove macro definition.
	* sysdeps/unix/sysv/linux/alpha/kernel-features.h
	(__ASSUME_ST_INO_64_BIT): Do not undefine and define.
	* sysdeps/unix/sysv/linux/sh/kernel-features.h
	(__ASSUME_ST_INO_64_BIT): Likewise.
	* sysdeps/unix/sysv/linux/fxstat64.c: Do not include
	<kernel-features.h>.
	(___fxstat64) [_HAVE_STAT64___ST_INO && !__ASSUME_ST_INO_64_BIT]:
	Remove conditional code.
	* sysdeps/unix/sysv/linux/lxstat64.c: Do not include
	<kernel-features.h>.
	(___lxstat64) [_HAVE_STAT64___ST_INO && !__ASSUME_ST_INO_64_BIT]:
	Remove conditional code.
	* sysdeps/unix/sysv/linux/xstat64.c: Do not include
	<kernel-features.h>.
	(___xstat64) [_HAVE_STAT64___ST_INO && !__ASSUME_ST_INO_64_BIT]:
	Remove conditional code.
	* sysdeps/unix/sysv/linux/xstatconv.c: Do not include
	<kernel-features.h>.
	(__xstat32_conv) [_HAVE_STAT64___ST_INO]: Remove conditional code.
	[!_HAVE_STAT64___ST_INO]: Make code unconditional.