libipt: use sysconf(_SC_PAGESIZE) instead of PAGE_SIZE

This fixes #11.

Change-Id: I45a62dbb10ea84e5e408532ff996b2028d85e93b
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
diff --git a/libipt/src/posix/pt_section_posix.c b/libipt/src/posix/pt_section_posix.c
index feb5913..0415ed0 100644
--- a/libipt/src/posix/pt_section_posix.c
+++ b/libipt/src/posix/pt_section_posix.c
@@ -39,7 +39,6 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
-#include <sys/user.h>
 #include <sys/mman.h>
 #include <fcntl.h>
 #include <unistd.h>
@@ -111,7 +110,7 @@
 	offset = section->offset;
 	size = section->size;
 
-	adjustment = offset % PAGE_SIZE;
+	adjustment = offset % sysconf(_SC_PAGESIZE);
 
 	offset -= adjustment;
 	size += adjustment;