[thread.lock.general] Remove superfluous whitespace (#8710)

Author: Andreas-Krug

source/threads.tex

@@ -8152,9 +8152,9 @@
   struct adopt_lock_t  { };     // assume the calling thread has already
                                 // obtained mutex ownership and manage it
 
-  inline constexpr defer_lock_t   defer_lock { };
-  inline constexpr try_to_lock_t  try_to_lock { };
-  inline constexpr adopt_lock_t   adopt_lock { };
+  inline constexpr defer_lock_t  defer_lock { };
+  inline constexpr try_to_lock_t try_to_lock { };
+  inline constexpr adopt_lock_t  adopt_lock { };
 }
 \end{codeblock}