x86-64: Fix alignment of jiffies variable

    It's declared __attribute__((aligned(16)) but it's explicitly
    not aligned.  This is probably harmless but it's a bit
    embarrassing.

    Signed-off-by: Andy Lutomirski <luto@mit.edu>
    Cc: Jesper Juhl <jj@chaosbits.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Arjan van de Ven <arjan@infradead.org>
    Cc: Jan Beulich <JBeulich@novell.com>
    Cc: richard -rw- weinberger <richard.weinberger@gmail.com>
    Cc: Mikael Pettersson <mikpe@it.uu.se>
    Cc: Andi Kleen <andi@firstfloor.org>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
    Cc: Valdis.Kletnieks@vt.edu
    Cc: pageexec@freemail.hu
    Link: http://lkml.kernel.org/r/5f3bc5542e9aaa9382d53f153f54373165cdef89.1307292171.git.luto@mit.edu
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
x86-64: Document some of entry_64.S

    Signed-off-by: Andy Lutomirski <luto@mit.edu>
    Cc: Jesper Juhl <jj@chaosbits.net>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Arjan van de Ven <arjan@infradead.org>
    Cc: Jan Beulich <JBeulich@novell.com>
    Cc: richard -rw- weinberger <richard.weinberger@gmail.com>
    Cc: Mikael Pettersson <mikpe@it.uu.se>
    Cc: Andi Kleen <andi@firstfloor.org>
    Cc: Brian Gerst <brgerst@gmail.com>
    Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
    Cc: Valdis.Kletnieks@vt.edu
    Cc: pageexec@freemail.hu
    Link: http://lkml.kernel.org/r/fc134867cc550977cc996866129e11a16ba0f9ea.1307292171.git.luto@mit.edu
    Signed-off-by: Ingo Molnar <mingo@elte.hu>