library: remove procps_pagesize_get()

This is actually a systemcall getpagesize(2) or it is defined
in configure using a variety of methods, including a default
hard coded value as a last resort.

There is no need to have this in libprocps

proc/sysinfo.h

@@ -11,7 +11,6 @@ extern int have_privs;             /* boolean, true if setuid or similar */
 long procps_cpu_count(void);
 long procps_hertz_get(void);
 int procps_loadavg(double *av1, double *av5, double *av15);
-long procps_pagesize_get(void);
 
 #define BUFFSIZE (64*1024)
 typedef unsigned long long jiff;