[gdb/testsuite] Add aranges to gdb.dwarf2/dw2-dir-file-name.exp

Since commit 52b920c5d20 ("[gdb/testsuite] Fix gdb.dwarf2/dw2-dir-file-name.exp
for ppc64le"), the test-case fails with target board cc-with-debug-names, due
to missing .debug_aranges info.

Add the missing .debug_aranges info.

Also add a file_id option to Dwarf::assemble, to make it possible to contribute
to an already open file.

Tested on x86_64-linux.

gdb/testsuite/gdb.dwarf2/dw2-dir-file-name.exp

@@ -317,6 +317,22 @@ puts -nonewline $f "\
 "
 out_compdir out_cu
 
+Dwarf::assemble { add_dummy_cus 0 file_id $f } {
+    global func_info_names
+
+    foreach name $func_info_names {
+	global ${name}_start
+	global ${name}_end
+	set name_start [set ${name}_start]
+	set name_end [set ${name}_end]
+
+	set cu_label .L${name}_begin
+	aranges {} cu_label {
+	    arange {} $name_start "$name_end - $name_start"
+	}
+    }
+}
+
 puts $f "  .section .debug_line"
 out_compdir out_line
 

gdb/testsuite/lib/dwarf.exp

@@ -3193,6 +3193,9 @@ namespace eval Dwarf {
     #           - the name of the file where the generated assembly
     #             code is written.
     #             default = "".
+    # file_id <tcl channel identifier>
+    #           - open file where the generated assemble core is written.
+    #             default = "".
     #  add_dummy_cus <0|1>
     #           - Whether to add dummy CUs before and after the CUs
     #             added in the BODY.
@@ -3233,6 +3236,7 @@ namespace eval Dwarf {
 
 	parse_options {
 	    { filename "" }
+	    { file_id "" }
 	    { add_dummy_cus 1 }
 	}
 
@@ -3241,7 +3245,12 @@ namespace eval Dwarf {
 	    set _initialized 1
 	}
 
-	set _output_file [open $filename w]
+	if { $file_id != "" } {
+	    set _output_file $file_id
+	} else {
+	    set _output_file [open $filename w]
+	}
+
 	set _cu_count -1
 	_empty_array _deferred_output
 	set _defer ""
@@ -3274,7 +3283,9 @@ namespace eval Dwarf {
 
 	_write_deferred_output
 
-	catch {close $_output_file}
+	if { $file_id == "" } {
+	    catch {close $_output_file}
+	}
 	set _output_file {}
     }
 }