[testsuite] dw2-const.S: fix type reference size on 64bit platforms.

The testcase was failing on various 64bit platforms, because the
debugging info said that the target type for a const type is a
4-byte reference.  In the asm file, I used a .long directive, but
the size of .long is of course dependent on the platform.  This
replaces this .long by a .4byte directive.

gdb/testsuite/ChangeLog:

        * gdb.dwarf2/dw2-const.S: Use .4byte to reference the target
        type of our const type.

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2010-09-22  Joel Brobecker  <brobecker@adacore.com>
+
+	* gdb.dwarf2/dw2-const.S: Use .4byte to reference the target
+	type of our const type.
+
 2010-09-22  Sami Wagiaalla  <swagiaal@redhat.com>
 
 	* gdb.cp/pr12028.cc: New.

gdb/testsuite/gdb.dwarf2/dw2-const.S

@@ -55,7 +55,7 @@ func_cu1:
 
 .Ltype_const:
         .uleb128        0x9                     /* Abbrev: DW_TAG_const_type */
-        .long           .Ltype_int-.Lcu1_begin  /* DW_AT_type */
+        .4byte           .Ltype_int-.Lcu1_begin  /* DW_AT_type */
 
 	/* func_cu1 */
 	.uleb128	2			/* Abbrev: DW_TAG_subprogram */