Add several tests for bad symlinks, including immutable flags, zero

i_size, too large i_size, and i_size_high set.

tests/f_badsymlinks/expect.1

@@ -0,0 +1,53 @@
+Pass 1: Checking inodes, blocks, and sizes
+Special (device/socket/fifo) inode 18 has immutable or append-only flag set.
+Clear? yes
+
+Inode 19 has illegal block(s).  Clear? yes
+
+Illegal block #0 (1234567890) in inode 19.  CLEARED.
+Inode 19, i_blocks is 2, should be 0.  Fix? yes
+
+Special (device/socket/fifo) inode 20 has immutable or append-only flag set.
+Clear? yes
+
+Pass 2: Checking directory structure
+Inode 17 (/empty_link) is a symlink with a bad size (0)
+Clear? yes
+
+Inode 13 (/long_fastlink) is a fast symlink with a bad size (99)
+Clear? yes
+
+Inode 14 (/long_link) is a symlink with a bad size (1234567890)
+Clear? yes
+
+Inode 16 (/high_link) is a symlink with a bad size (4294967358)
+Clear? yes
+
+Inode 12 (/empty_fastlink) is a fast symlink with a bad size (0)
+Clear? yes
+
+Inode 19 (/bad_link) is a fast symlink with a bad size (62)
+Clear? yes
+
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+Block bitmap differences:  -26
+Fix? yes
+
+Free blocks count wrong for group #0 (997, counted=1001).
+Fix? yes
+
+Free blocks count wrong (997, counted=1001).
+Fix? yes
+
+Free inodes count wrong for group #0 (12, counted=18).
+Fix? yes
+
+Free inodes count wrong (12, counted=18).
+Fix? yes
+
+
+test_filesys: ***** FILE SYSTEM WAS MODIFIED *****
+test_filesys: 14/32 files (0.0% non-contiguous), 23/1024 blocks
+Exit status is 1

tests/f_badsymlinks/expect.2

@@ -0,0 +1,7 @@
+Pass 1: Checking inodes, blocks, and sizes
+Pass 2: Checking directory structure
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+test_filesys: 14/32 files (0.0% non-contiguous), 23/1024 blocks
+Exit status is 0

tests/f_badsymlinks/name

@@ -0,0 +1 @@
+corrupted fast symlinks