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/libprocps.sym

@@ -36,7 +36,6 @@ global:
 	procps_meminfo_unref;
 	procps_meminfo_get;
 	procps_meminfo_get_chain;
-	procps_pagesize_get;
 	procps_stat_new;
 	procps_stat_read;
 	procps_stat_read_jiffs;