meminfo: Replace sys/io.h by direct register accesses.

[daym]

Signed-off-by: Danny Milosavljevic dannym@scratchpost.org

sys/io.h has been removed in glibc 2.30.

https://sourceware.org/legacy-ml/libc-alpha/2019-08/msg00029.html

• On 32-bit Arm, support for the port-based I/O emulation and the <sys/io.h>
  header have been removed.

It's easy to just directly access--so I did that...

[apritzel]

So @vkochan had a similar patch #122, but he did not reply to the comments, and this version here seems to address them all fine.
So we should go ahead with this one. Just compile tested (and I had issues already on Ubuntu 18.04's glibc 2.27).