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>

proc/whattime.h

@@ -1,13 +1,13 @@
 #ifndef PROC_WHATTIME_H
 #define PROC_WHATTIME_H
 
-#include "procps.h"
+#include <proc/procps.h>
 
-EXTERN_C_BEGIN
+__BEGIN_DECLS
 
 extern void print_uptime(int human_readable);
 extern char *sprint_uptime(int human_readable);
 
-EXTERN_C_END
+__END_DECLS
 
 #endif