[gdb/testsuite] Handle core without build-id in gdb.base/corefile-buildid.exp

On aarch64-linux (debian 12), when running test-case gdb.base/corefile-buildid.exp, I get:
...
expecting exec file "debugdir-exec/.build-id/ec/f10ec5d39648774f8c35d3cf757c8db52f5163"
info files^M
Local core dump file:^M
        `build-exec/corefile-buildid.core', file type elf64-littleaarch64.^M
        0x0000aaaac1d70000 - 0x0000aaaac1d71000 is load1^M
	...
        0x0000ffffffa8b000 - 0x0000ffffffaac000 is load16^M
(gdb) FAIL: gdb.base/corefile-buildid.exp: exec: info files
...

The problem is that the test-case expect the build-id to be available in the
core file, while it isn't.

Fix this by detecting that the build-id isn't available in the core file using eu-readelf, as in
gdb.base/coredump-filter-build-id.exp.

Tested on aarch64-linux.

Approved-By: Tom Tromey <tom@tromey.com>
1 file changed