[Ada] Make GNAT.Array_Split a preelaborable unit

This patch makes GNAT.Array_Split a preelaborable unit. As a result, it can be
withed by other preelaborated untis.

2018-06-11  Hristian Kirtchev  <kirtchev@adacore.com>

gcc/ada/

	* libgnat/g-arrspl.ads: Add pragma Preelaborate.

gcc/testsuite/

	* gnat.dg/gnat_array_split1.adb, gnat.dg/gnat_array_split1.ads: New
	testcase.

From-SVN: r261419

gcc/ada/ChangeLog

+2018-06-11  Hristian Kirtchev  <kirtchev@adacore.com>
+
+	* libgnat/g-arrspl.ads: Add pragma Preelaborate.
+
 2018-06-11  Arnaud Charlet  <charlet@adacore.com>
 
 	* exp_ch4.adb (Expand_Record_Equality): Remove extraneous "True and

gcc/ada/libgnat/g-arrspl.ads

@@ -56,6 +56,7 @@ generic
    --  Returns True if Item is found in Set, False otherwise
 
 package GNAT.Array_Split is
+   pragma Preelaborate;
 
    Index_Error : exception;
    --  Raised by all operations below if Index > Field_Count (S)

gcc/testsuite/ChangeLog

+2018-06-11  Hristian Kirtchev  <kirtchev@adacore.com>
+
+	* gnat.dg/gnat_array_split1.adb, gnat.dg/gnat_array_split1.ads: New
+	testcase.
+
 2018-06-11  Javier Miranda  <miranda@adacore.com>
 
 	* gnat.dg/prot4.adb: New testcase.

gcc/testsuite/gnat.dg/gnat_array_split1.adb

+--  { dg-do compile }
+
+package body GNAT_Array_Split1 is
+   procedure Dummy is null;
+end GNAT_Array_Split1;

gcc/testsuite/gnat.dg/gnat_array_split1.ads

+with GNAT.Array_Split;
+
+package GNAT_Array_Split1 is
+   pragma Preelaborate;
+   procedure Dummy;
+end GNAT_Array_Split1;