Added out-of-order write testing to emubd

Some forms of storage, mainly anything with an FTL, eMMC, SD, etc, do
not guarantee a strict write order for writes to different blocks. It
would be good to test that this doesn't break littlefs.

This adds LFS_EMUBD_POWERLOSS_OOO to lfs_emubd, which tells lfs_emubd to
try to break any order-dependent code on powerloss.

The behavior right now is a bit simple, but does result in test
breakage:

1. Save the state of the block on first write (erase really) after
   sync/init.

2. On powerloss, revert the first write to its original state.

This might be a bit confusing when debugging, since the block will
appear to time-travel, but doing anything fancier would make emubd quite
a bit more complicated.

You could also get a bit fancier with which/how many blocks to revert,
but this should at least be sufficient to make sure bd sync calls are in
the right place.

tests/test_dirs.toml

@@ -181,6 +181,10 @@ code = '''
 defines.N = [5, 11]
 if = 'BLOCK_COUNT >= 4*N'
 reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
 code = '''
     lfs_t lfs;
     int err = lfs_mount(&lfs, cfg);
@@ -439,6 +443,10 @@ code = '''
 defines.N = [5, 25]
 if = 'N < BLOCK_COUNT/2'
 reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
 code = '''
     lfs_t lfs;
     int err = lfs_mount(&lfs, cfg);

tests/test_files.toml

@@ -310,6 +310,10 @@ defines.SIZE = [32, 0, 7, 2049]
 defines.CHUNKSIZE = [31, 16, 65]
 defines.INLINE_MAX = [0, -1, 8]
 reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
 code = '''
     lfs_t lfs;
     int err = lfs_mount(&lfs, cfg);
@@ -500,6 +504,10 @@ code = '''
 [cases.test_files_many_power_loss]
 defines.N = 300
 reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
 code = '''
     lfs_t lfs;
     int err = lfs_mount(&lfs, cfg);

tests/test_interspersed.toml

@@ -195,6 +195,10 @@ code = '''
 defines.SIZE = [10, 100]
 defines.FILES = [4, 10, 26] 
 reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
 code = '''
     lfs_t lfs;
     lfs_file_t files[FILES];

tests/test_move.toml

@@ -357,6 +357,10 @@ code = '''
 
 [cases.test_move_reentrant_file]
 reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
 code = '''
     lfs_t lfs;
     int err = lfs_mount(&lfs, cfg);
@@ -839,6 +843,10 @@ code = '''
 
 [cases.test_reentrant_dir]
 reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
 code = '''
     lfs_t lfs;
     int err = lfs_mount(&lfs, cfg);

tests/test_seek.toml

@@ -329,6 +329,10 @@ code = '''
 # must be power-of-2 for quadratic probing to be exhaustive
 defines.COUNT = [4, 64, 128]
 reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
 code = '''
     lfs_t lfs;
     int err = lfs_mount(&lfs, cfg);

tests/test_superblocks.toml

@@ -32,6 +32,10 @@ code = '''
 # reentrant format
 [cases.test_superblocks_reentrant_format]
 reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
 code = '''
     lfs_t lfs;
     int err = lfs_mount(&lfs, cfg);
@@ -174,6 +178,10 @@ code = '''
 defines.BLOCK_CYCLES = [2, 1]
 defines.N = 24
 reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
 code = '''
     lfs_t lfs;
     int err = lfs_mount(&lfs, cfg);

tests/test_truncate.toml

@@ -231,6 +231,10 @@ defines.SMALLSIZE = [4, 512]
 defines.MEDIUMSIZE = [0, 3, 4, 5, 31, 32, 33, 511, 512, 513, 1023, 1024, 1025]
 defines.LARGESIZE = 2048
 reentrant = true
+defines.POWERLOSS_BEHAVIOR = [
+    'LFS_EMUBD_POWERLOSS_NOOP',
+    'LFS_EMUBD_POWERLOSS_OOO',
+]
 code = '''
     lfs_t lfs;
     int err = lfs_mount(&lfs, cfg);