tools/libs/stat: fix broken build

Making getBridge() static triggered a build error with some gcc versions:

error: 'strncpy' output may be truncated copying 15 bytes from a string of
length 255 [-Werror=stringop-truncation]

Fix that by using a buffer with 256 bytes instead.

Fixes: 6d0ec05390 ("tools: split libxenstat into new tools/libs/stat directory")
Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Wei Liu <wl@xen.org>

tools/libs/stat/xenstat_linux.c

@@ -78,7 +78,7 @@ static void getBridge(char *excludeName, char *result, size_t resultLen)
 				sprintf(tmp, "/sys/class/net/%s/bridge", de->d_name);
 
 				if (access(tmp, F_OK) == 0) {
-					strncpy(result, de->d_name, resultLen - 1);
+					strncpy(result, de->d_name, resultLen);
 					result[resultLen - 1] = 0;
 				}
 		}
@@ -264,7 +264,7 @@ int xenstat_collect_networks(xenstat_node * node)
 {
 	/* Helper variables for parseNetDevLine() function defined above */
 	int i;
-	char line[512] = { 0 }, iface[16] = { 0 }, devBridge[16] = { 0 }, devNoBridge[17] = { 0 };
+	char line[512] = { 0 }, iface[16] = { 0 }, devBridge[256] = { 0 }, devNoBridge[257] = { 0 };
 	unsigned long long rxBytes, rxPackets, rxErrs, rxDrops, txBytes, txPackets, txErrs, txDrops;
 
 	struct priv_data *priv = get_priv_data(node->handle);