Fix the build: error message quote

The problem here is the quote mark is for English's
possessiveness rather than a quote but the error message
format detection is too simple so it warns which causes
-Werror to fail.

Committed as obvious after a quick build.

gcc/ChangeLog:

	* tree-cfg.cc (verify_gimple_assign): Remove quote
	mark to shut up the warning.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>

gcc/tree-cfg.cc

@@ -4842,7 +4842,7 @@ verify_gimple_assign (gassign *stmt)
       tree lhs = gimple_assign_lhs (stmt);
       if (is_gimple_reg (lhs))
 	{
-	  error ("nontemporal store's lhs cannot be a gimple register");
+	  error ("nontemporal store lhs cannot be a gimple register");
 	  debug_generic_stmt (lhs);
 	  return true;
 	}