[Ada] Turn Ada.Calendar.Epoch_Offset into a function

2018-05-29  Arnaud Charlet  <charlet@adacore.com>

gcc/ada/

	* libgnat/a-calend.ads, libgnat/a-calend.adb (Epoch_Offset): Make it a
	function.

From-SVN: r260878

gcc/ada/ChangeLog

+2018-05-29  Arnaud Charlet  <charlet@adacore.com>
+
+	* libgnat/a-calend.ads, libgnat/a-calend.adb (Epoch_Offset): Make it a
+	function.
+
 2018-05-29  Olivier Hainque  <hainque@adacore.com>
 
 	* libgnat/system-vxworks7-ppc-rtp.ads: New file.

gcc/ada/libgnat/a-calend.adb

@@ -500,6 +500,15 @@ is
       return D;
    end Day;
 
+   ------------------
+   -- Epoch_Offset --
+   ------------------
+
+   function Epoch_Offset return Time_Rep is
+   begin
+      return (136 * 365 + 44 * 366) * Nanos_In_Day;
+   end Epoch_Offset;
+
    -------------
    -- Is_Leap --
    -------------

gcc/ada/libgnat/a-calend.ads

@@ -221,8 +221,9 @@ private
    --  with overloading ambiguities in the body if we tried to use Time as an
    --  internal computational type.
 
-   Epoch_Offset : constant Time_Rep := (136 * 365 + 44 * 366) * Nanos_In_Day;
-   --  The difference between 2150-1-1 UTC and 1970-1-1 UTC expressed in
+   function Epoch_Offset return Time_Rep;
+   pragma Inline (Epoch_Offset);
+   --  Return the difference between 2150-1-1 UTC and 1970-1-1 UTC expressed in
    --  nanoseconds. Note that year 2100 is non-leap.
 
    Days_In_Month : constant array (Month_Number) of Day_Number :=