unlock all fd mutexes in reverse order

Some functions acquire mutexes for multiple file descriptors.
This commit ensures that the mutexes are released in the
reverse order that they are aquired.

Author: cjihrig

src/fd_table.c

@@ -366,8 +366,8 @@ uvwasi_errno_t uvwasi_fd_table_renumber(struct uvwasi_s* uvwasi,
   r = uv_fs_close(NULL, &req, dst_entry->fd, NULL);
   uv_fs_req_cleanup(&req);
   if (r != 0) {
-    uv_mutex_unlock(&dst_entry->mutex);
     uv_mutex_unlock(&src_entry->mutex);
+    uv_mutex_unlock(&dst_entry->mutex);
     err = uvwasi__translate_uv_error(r);
     goto exit;
   }

src/uvwasi.c

@@ -1821,9 +1821,9 @@ uvwasi_errno_t uvwasi_path_link(uvwasi_t* uvwasi,
 
   err = UVWASI_ESUCCESS;
 exit:
-  uv_mutex_unlock(&old_wrap->mutex);
+  uv_mutex_unlock(&new_wrap->mutex);
   if (old_fd != new_fd)
-    uv_mutex_unlock(&new_wrap->mutex);
+    uv_mutex_unlock(&old_wrap->mutex);
   return err;
 }
 
@@ -2136,9 +2136,9 @@ uvwasi_errno_t uvwasi_path_rename(uvwasi_t* uvwasi,
 
   err = UVWASI_ESUCCESS;
 exit:
-  uv_mutex_unlock(&old_wrap->mutex);
+  uv_mutex_unlock(&new_wrap->mutex);
   if (old_fd != new_fd)
-    uv_mutex_unlock(&new_wrap->mutex);
+    uv_mutex_unlock(&old_wrap->mutex);
 
   return err;
 }