[Ada] Minor refactoring

2019-07-11  Piotr Trojanek  <trojanek@adacore.com>

gcc/ada/

	* checks.adb: Fix typo in comment.
	* sem.adb (Semantics): Avoid repeated calls to
	In_Extended_Main_Source_Unit by reusing an already-cached
	result.
	* sem_util.adb (First_Global): Fix style.

From-SVN: r273406

gcc/ada/ChangeLog

+2019-07-11  Piotr Trojanek  <trojanek@adacore.com>
+
+	* checks.adb: Fix typo in comment.
+	* sem.adb (Semantics): Avoid repeated calls to
+	In_Extended_Main_Source_Unit by reusing an already-cached
+	result.
+	* sem_util.adb (First_Global): Fix style.
+
 2019-07-11  Yannick Moy  <moy@adacore.com>
 
 	* sem_res.adb (Resolve_Call): Do not perform dimensionality

gcc/ada/checks.adb

@@ -7056,7 +7056,7 @@ package body Checks is
             Convert_And_Check_Range;
          end if;
 
-      --  Note that at this stage we now that the Target_Base_Type is not in
+      --  Note that at this stage we know that the Target_Base_Type is not in
       --  the range of the Source_Base_Type (since even the Target_Type itself
       --  is not in this range). It could still be the case that Source_Type is
       --  in range of the target base type since we have not checked that case.

gcc/ada/sem.adb

@@ -1579,7 +1579,7 @@ package body Sem is
            and then Nkind (Unit (Comp_Unit)) in N_Proper_Body
            and then (Nkind (Unit (Comp_Unit)) /= N_Subprogram_Body
                        or else not Acts_As_Spec (Comp_Unit))
-           and then not In_Extended_Main_Source_Unit (Comp_Unit)
+           and then not Ext_Main_Source_Unit
          then
             null;
 

gcc/ada/sem_util.adb

@@ -8703,6 +8703,8 @@ package body Sem_Util is
       Global  : Node_Id := Empty;
       Body_Id : Entity_Id;
 
+   --  Start of processing for First_Global
+
    begin
       pragma Assert (Nam_In (Global_Mode, Name_In_Out,
                                           Name_Input,