sysv: linux: Add 64-bit time_t variant for msgctl

sysv: linux: Add 64-bit time_t variant for msgctl

To provide a y2038 safe interface a new symbol __msgctl64 is added
and __msgctl is change to call it instead (it adds some extra buffer
coping for the 32 bit time_t implementation).

Two new structures are added:

  1. kernel_msqid64_ds: used internally only on 32-bit architectures
     to issue the syscall.  A handful of architectures (hppa, i386, mips,
     powerpc32, and sparc32) require specific implementations due to
     their kernel ABI.

  2. msqid_ds64: this is only for __TIMESIZE != 64 to use along with
     the 64-bit msgctl.  It is different than the kernel struct because
     the exported 64-bit time_t might require different alignment
     depending on the architecture ABI.

So the resulting implementation does:

  1. For 64-bit architectures it assumes msqid_ds already contains
     64-bit time_t fields and will result in just the __msgctl symbol
     using the __msgctl64 code.  The msgid_ds argument is passed as-is
     to the syscall.

  2. For 32-bit architectures with default 64-bit time_t (newer ABIs
     such riscv32 or arc), it will also result in only one exported
     symbol but with the required high/low time handling.

  3. Finally for 32-bit architecture with both 32-bit and 64-bit time_t
     support we follow the already set way to provide one symbol with
     64-bit time_t support and implement the 32-bit time_t support using
     the 64-bit time_t.

     The default 32-bit symbol will allocate and copy the msqid_ds
     over multiple buffers, but this should be deprecated in favor
     of the __msgctl64 anyway.

Checked on i686-linux-gnu and x86_64-linux-gnu.  I also did some sniff
tests on powerpc, powerpc64, mips, mips64, armhf, sparcv9, and
sparc64.

Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Tested-by: Alistair Francis <alistair.francis@wdc.com>