[gdb/testsuite] Add aranges in gdb.dwarf2/dwzbuildid.exp

[gdb/testsuite] Add aranges in gdb.dwarf2/dwzbuildid.exp

While investigating the execs of gdb.dwarf2/dwzbuildid.exp using readelf I ran
into a warning:
...
$ readelf -w dwzbuildid-ok > READELF
readelf: Warning: .debug_info offset of 0x2e in .debug_aranges section does not
point to a CU header.
...

AFAICT, the warning is incorrect, I've filed PR binutils/30835 about that.

While looking at the .debug_aranges section, I noticed that the entries for
the CUs generated by the dwarf assembler are missing.

Fix this by adding the missing .debug_aranges entries.

Tested on x86_64-linux.