Fixed off-by-one null terminator in tests

Found by mr-at-eo

tests/test_paths.sh

@@ -179,7 +179,7 @@ echo "--- Really big path test ---"
 scripts/test.py << TEST
     lfs_mount(&lfs, &cfg) => 0;
     memset(path, 'w', LFS_NAME_MAX);
-    path[LFS_NAME_MAX+1] = '\0';
+    path[LFS_NAME_MAX] = '\0';
     lfs_mkdir(&lfs, path) => 0;
     lfs_remove(&lfs, path) => 0;
     lfs_file_open(&lfs, &file, path,
@@ -189,7 +189,7 @@ scripts/test.py << TEST
 
     memcpy(path, "coffee/", strlen("coffee/"));
     memset(path+strlen("coffee/"), 'w', LFS_NAME_MAX);
-    path[strlen("coffee/")+LFS_NAME_MAX+1] = '\0';
+    path[strlen("coffee/")+LFS_NAME_MAX] = '\0';
     lfs_mkdir(&lfs, path) => 0;
     lfs_remove(&lfs, path) => 0;
     lfs_file_open(&lfs, &file, path,