Adjust to new text that "file" outputs for ARM linux kernels:
"ARM OpenFirmware FORTH Dictionary..."
Make test_bootimg_kernel pass again, which was failing with:
AssertionError: assert 'heimdall-isorec' in 'File is not an Android ...
postmarketOS/pmaports!700 adds a new "deviceinfo_bootimg_dtb_second"
option that places the DTB in the "second" area of the Android boot
image.
Attempt to detect this automatically by checking the extracted
second binary for the FDT magic (0xd00dfeed).
mkbootimg from osm0sis changed the filename of the dtb section in [1]
which breaks the detection of qcdt in pmbootstrap.
Fix this by adjusting the filename pmbootstrap checks to match the
unpackbootimg behavior.
[1] d8222a4d
We are analyzing the `boot.img` with `file` before we send it to
`unpackbootimg`. File does not recognize all kinds of `boot.img` files,
which `unpackbootimg` can extract, so we need a way to skip this check.
Details:
* Add `-f` parameter, continues extraction with a warning if the file
seems to be invalid
* Tell the user that `-f` can be used if the `boot.img` is invalid and
it's not specified
* Consistent spelling of `boot.img` instead of `bootimg` in messages
Fixes#1608
Use case: `mkbootimg` provides the `unpackbootimg` package. When
running `pmb.chroot.apk.install(args,"unpackbootimg")`, it was not
able to properly build the package.
Reproducing the error:
```
sudo rm ~/.local/var/pmbootstrap/packages/x86_64/mkbootimg*
pmbootstrap index
pmbootstrap --mirror-pmOS="" chroot --add=unpackbootimg
```
Or alternatively (simpler but less illustrative):
```
pmbootstrap build unpackbootimg --force
```
Closes#441. Adjust bootimg_analyze code:
* Install mkbootimg (which now provides unpackbootimg) instead of
unpackbootimg. In theory, pmbootstrap should recognize this
automatically, however right now it does not yet handle this case.
* The file names of the extracted files have changed.
