[Ada] Fix bogus style check failure with pragma Style_Checks (Off)

This fixes a bogus style check failure for long lines in rare cases
where the compiler is invoked, with a -gnatyX switch where X is neither
'm' nor 'M', on a unit which contains "with" clauses for other units
that contain a pragma Style_Checks (Off).

2019-08-13  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* sem.adb (Do_Analyze): Recompute Style_Check_Max_Line_Length
	after restoring Style_Max_Line_Length.

From-SVN: r274352

gcc/ada/ChangeLog

+2019-08-13  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* sem.adb (Do_Analyze): Recompute Style_Check_Max_Line_Length
+	after restoring Style_Max_Line_Length.
+
 2019-08-13  Arnaud Charlet  <charlet@adacore.com>
 
 	* sem_ch13.adb (Check_Iterator_Functions): Protect against

gcc/ada/sem.adb

@@ -1395,6 +1395,7 @@ package body Sem is
          Restore_Scope_Stack  (List);
          Restore_Ghost_Region (Saved_GM, Saved_IGR);
          Style_Max_Line_Length := Saved_ML;
+         Style_Check_Max_Line_Length := Style_Max_Line_Length /= 0;
       end Do_Analyze;
 
       --  Local variables