Kernel: Allow to remove files from sticky directory if user owns it

It's what the Linux chmod(1) manpage says (in the 'Restricted Deletion
Flag or Sticky Bit' section), and it just makes sense to me. :^)

Kernel/FileSystem/VirtualFileSystem.cpp

@@ -645,7 +645,7 @@ ErrorOr<void> VirtualFileSystem::rename(Credentials const& credentials, Custody&
         return EACCES;
 
     if (old_parent_inode.metadata().is_sticky()) {
-        if (!credentials.is_superuser() && old_inode.metadata().uid != credentials.euid())
+        if (!credentials.is_superuser() && old_parent_inode.metadata().uid != credentials.euid() && old_inode.metadata().uid != credentials.euid())
             return EACCES;
     }
 
@@ -807,7 +807,7 @@ ErrorOr<void> VirtualFileSystem::unlink(Credentials const& credentials, StringVi
         return EACCES;
 
     if (parent_inode.metadata().is_sticky()) {
-        if (!credentials.is_superuser() && inode.metadata().uid != credentials.euid())
+        if (!credentials.is_superuser() && parent_inode.metadata().uid != credentials.euid() && inode.metadata().uid != credentials.euid())
             return EACCES;
     }