Simplified config

Before, the lfs had multiple paths to determine config options:
- lfs_config struct passed during initialization
- lfs_bd_info struct passed during block device initialization
- compile time options

This allowed different developers to provide their own needs
to the filesystem, such as the block device capabilities and
the higher level user's own tweaks.

However, this comes with additional complexity and action required
when the configurations are incompatible.

For now, this has been reduced to all information (including block
device function pointers) being passed through the lfs_config struct.
We just defer more complicated handling of configuration options to
the top level user.

This simplifies configuration handling and gives the top level user
the responsibility to handle configuration, which they probably would
have wanted to do anyways.

tests/test_orphan.sh

@@ -4,12 +4,12 @@ set -eu
 echo "=== Orphan tests ==="
 rm -rf blocks
 tests/test.py << TEST
-    lfs_format(&lfs, &config) => 0;
+    lfs_format(&lfs, &cfg) => 0;
 TEST
 
 echo "--- Orphan test ---"
 tests/test.py << TEST
-    lfs_mount(&lfs, &config) => 0;
+    lfs_mount(&lfs, &cfg) => 0;
     lfs_mkdir(&lfs, "parent") => 0;
     lfs_mkdir(&lfs, "parent/orphan") => 0;
     lfs_mkdir(&lfs, "parent/child") => 0;
@@ -19,7 +19,7 @@ TEST
 # linked-list entry and should orphan the child
 rm -v blocks/8
 tests/test.py << TEST
-    lfs_mount(&lfs, &config) => 0;
+    lfs_mount(&lfs, &cfg) => 0;
     lfs_stat(&lfs, "parent/orphan", &info) => LFS_ERROR_NO_ENTRY;
     unsigned before = 0;
     lfs_traverse(&lfs, test_count, &before) => 0;