library: sysstat and vmstat api changes

library: sysstat and vmstat api changes

Use the standard libc declarations.
For protecting the headers for C++ procps used to have its
own defines, this change makes them use the standard libc ones.

getstat() -> procps_stat_*
vminfo() -> procps_vmstat_*
These two components of the library now use the newer version of
the API with less exposed global variables. The old methods are
there for now.

Signed-off-by: Craig Small <csmall@enc.com.au>