Fixed standard name mismatch LFS_ERR_EXISTS -> LFS_ERR_EXIST

Matches the standard EEXIST name found on most systems. Other than
this name, all other common constant names were consistent in this
manner.

lfs.c

@@ -819,7 +819,7 @@ int lfs_mkdir(lfs_t *lfs, const char *path) {
  lfs_entry_t entry;
  err = lfs_dir_find(lfs, &cwd, &entry, &path);
  if (err != LFS_ERR_NOENT || strchr(path, '/') != NULL) {
- return err ? err : LFS_ERR_EXISTS;
+ return err ? err : LFS_ERR_EXIST;
  }
 
  // build up new directory
@@ -1219,7 +1219,7 @@ int lfs_file_open(lfs_t *lfs, lfs_file_t *file,
  } else if (entry.d.type == LFS_TYPE_DIR) {
  return LFS_ERR_ISDIR;
  } else if (flags & LFS_O_EXCL) {
- return LFS_ERR_EXISTS;
+ return LFS_ERR_EXIST;
  }
 
  // setup file struct

lfs.h

@@ -45,7 +45,7 @@ enum lfs_error {
  LFS_ERR_IO = -5, // Error during device operation
  LFS_ERR_CORRUPT = -52, // Corrupted
  LFS_ERR_NOENT = -2, // No directory entry
- LFS_ERR_EXISTS = -17, // Entry already exists
+ LFS_ERR_EXIST  = -17, // Entry already exists
  LFS_ERR_NOTDIR = -20, // Entry is not a dir
  LFS_ERR_ISDIR = -21, // Entry is a dir
  LFS_ERR_INVAL = -22, // Invalid parameter

tests/test_dirs.sh

@@ -56,7 +56,7 @@ TEST
 echo "--- Directory failures ---"
 tests/test.py << TEST
  lfs_mount(&lfs, &cfg) => 0;
- lfs_mkdir(&lfs, "potato") => LFS_ERR_EXISTS;
+ lfs_mkdir(&lfs, "potato") => LFS_ERR_EXIST;
  lfs_dir_open(&lfs, &dir[0], "tomato") => LFS_ERR_NOENT;
  lfs_dir_open(&lfs, &dir[0], "burito") => LFS_ERR_NOTDIR;
  lfs_file_open(&lfs, &file[0], "tomato", LFS_O_RDONLY) => LFS_ERR_NOENT;