Require string merging support in gnat.dg/string_merge?.adb etc.

	* gcc.dg/merge-all-constants-2.c: Require string_merging support.
	* gnat.dg/string_merge1.adb: Likewise.
	* gnat.dg/string_merge2.adb: Likewise.

From-SVN: r264918

gcc/testsuite/ChangeLog

 2018-10-08  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
+	* gcc.dg/merge-all-constants-2.c: Require string_merging support.
+	* gnat.dg/string_merge1.adb: Likewise.
+	* gnat.dg/string_merge2.adb: Likewise.
+
+2018-10-08  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
+
 	* c-c++-common/Wprio-ctor-dtor.c: Require init_priority support.
 
 2018-10-08  Martin Liska  <mliska@suse.cz>

gcc/testsuite/gcc.dg/merge-all-constants-2.c

 /* { dg-do compile } */
+/* { dg-require-effective-target string_merging } */
 /* { dg-options "-w -O2 -fmerge-all-constants" } */
 
 const char str1[36] = "0123456789abcdefghijklmnopqrstuvwxyz";

gcc/testsuite/gnat.dg/string_merge1.adb

 -- { dg-do compile }
+-- { dg-require-effective-target string_merging }
 -- { dg-options "-O1 -fmerge-all-constants" }
 
 procedure String_Merge1 is

gcc/testsuite/gnat.dg/string_merge2.adb

 -- { dg-do compile }
+-- { dg-require-effective-target string_merging }
 -- { dg-options "-O1 -fmerge-all-constants" }
 
 procedure String_Merge2 is