Fix some gcc 8.1 snprintf overflow warnings

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>

hwloc/topology-linux.c

@@ -4880,7 +4880,7 @@ hwloc_linuxfs_block_class_fillinfos(struct hwloc_backend *backend __hwloc_attrib
   struct hwloc_linux_backend_data_s *data = backend->private_data;
 #endif
   FILE *file;
-  char path[256];
+  char path[296]; /* osdevpath <= 256 */
   char line[128];
   char vendor[64] = "";
   char model[64] = "";
@@ -5093,7 +5093,7 @@ hwloc_linuxfs_net_class_fillinfos(int root_fd,
 				  struct hwloc_obj *obj, const char *osdevpath)
 {
   struct stat st;
-  char path[256];
+  char path[296]; /* osdevpath <= 256 */
   char address[128];
   snprintf(path, sizeof(path), "%s/address", osdevpath);
   if (!hwloc_read_path_by_length(path, address, sizeof(address), root_fd)) {
@@ -5160,7 +5160,7 @@ static void
 hwloc_linuxfs_infiniband_class_fillinfos(int root_fd,
 					 struct hwloc_obj *obj, const char *osdevpath)
 {
-  char path[256];
+  char path[296]; /* osdevpath <= 256 */
   char guidvalue[20];
   unsigned i,j;
 
@@ -5281,7 +5281,7 @@ static void
 hwloc_linuxfs_mic_class_fillinfos(int root_fd,
 				  struct hwloc_obj *obj, const char *osdevpath)
 {
-  char path[256];
+  char path[296]; /* osdevpath <= 256 */
   char family[64];
   char sku[64];
   char sn[64];

hwloc/topology.c

@@ -1392,7 +1392,7 @@ hwloc___insert_object_by_cpuset(struct hwloc_topology *topology, hwloc_obj_t cur
         if (report_error) {
 	  char childstr[512];
 	  char objstr[512];
-	  char msg[1024];
+	  char msg[1100];
 	  hwloc__report_error_format_obj(objstr, sizeof(objstr), obj);
 	  hwloc__report_error_format_obj(childstr, sizeof(childstr), child);
 	  snprintf(msg, sizeof(msg), "%s intersects with %s without inclusion!", objstr, childstr);

utils/lstopo/lstopo-draw.c

@@ -1206,7 +1206,7 @@ output_draw(struct lstopo_output *loutput)
   time_t t;
   char text[3][128];
   unsigned ntext = 0;
-  char hostname[128] = "";
+  char hostname[122] = "";
   const char *forcedhostname = NULL;
   unsigned long hostname_size = sizeof(hostname);
   unsigned maxtextwidth = 0, textwidth;