misc: quiet minor compiler errors

Several compiler errors are quieted:
- zero-length gnu_printf format string
- unused variable
- uninitalized variable (though it isn't actually used for anything)
- fixed a bug in ext2fs_stat() if stat64() does not exist

Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
diff --git a/e2fsck/problem.c b/e2fsck/problem.c
index 0d56983..2c49493 100644
--- a/e2fsck/problem.c
+++ b/e2fsck/problem.c
@@ -1979,6 +1979,7 @@
 	e2fsck_t ctx;
 	int rc;
 
+	memset(&ctx, 0, sizeof(ctx)); /* just to quiet compiler */
 	rc = verify_problem_table(ctx);
 	if (rc == 0)
 		printf("e2fsck problem table verified\n");