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[libvirt] Fix wrong nodeinfo->mhz when cpufreq is enabled


I've written a little patch to fix wrong nodeinfo->mhz when the Linux
kernel module cpufreq and a typical governor like ondemand are loaded.
nodeinfo->mhz is then too low as libvirt just reads /proc/cpuinfo,
entry "cpu MHz". This patch reads


if existing and corrects nodeinfo->mhz if the value found is higher.
Using cpu0 is a crude hack but as discussed on IRC, considering different
governors/maximum frequencies per cpu/core would require changing the
nodeinfo struct, which would break the API.

Some more info: https://bugzilla.redhat.com/show_bug.cgi?id=559762

Please have a careful look at my patch, my last C is quite some time ago.
I tried to stick to linuxNodeInfoCPUPopulate, but f.e., checking for
"&& *p == '\0'" after virStrToLong_ui doesn't work and I'm wondering why
scaling_max_freq may not be terminated with by NUL? I also hope the file
handling is correct, but please have a look.

There is still some todo: Some logging would be helpful, maybe one of you
could point out which function best to use?

This is my first patch, so hopefully it follows in the next mail ;-)


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