vlib: clib_panic if sysconf() can't determine page size on startup

Account for the potential of sysconf() returning -1 if it can not
get the page size and make it a fatal error.

Coverity: 277313
Type: fix
Signed-off-by: Andrew Yourtchenko <ayourtch@gmail.com>
Change-Id: I8cae6a35ec2f745c37f1fe6557e5fa66720b4628
diff --git a/src/vppinfra/linux/mem.c b/src/vppinfra/linux/mem.c
index ec3328d..69f4363 100644
--- a/src/vppinfra/linux/mem.c
+++ b/src/vppinfra/linux/mem.c
@@ -103,6 +103,7 @@
 clib_mem_main_init ()
 {
   clib_mem_main_t *mm = &clib_mem_main;
+  long sysconf_page_size;
   uword page_size;
   void *va;
   int fd;
@@ -111,7 +112,12 @@
     return;
 
   /* system page size */
-  page_size = sysconf (_SC_PAGESIZE);
+  sysconf_page_size = sysconf (_SC_PAGESIZE);
+  if (sysconf_page_size < 0)
+    {
+      clib_panic ("Could not determine the page size");
+    }
+  page_size = sysconf_page_size;
   mm->log2_page_sz = min_log2 (page_size);
 
   /* default system hugeppage size */