mkbootimg: check dtb image size

- per aosp-mirror/platform_system_core@96fd887
- check all dt* image sizes
- clean up dt* error messages

unpackbootimg: fix unpacking Huawei "Cairo" signing

- Huawei boot.img has header_version=0 but "Cairo SIGN" at offset 1632 would confuse header.dtb_size so protect against this
- add similar protection for header.recovery_dtbo_size

mkbootimg: update for boot_img_hdr_v2

- switch to v2 and support new --dtb and --dtb_offset when --header_version 2 (or greater)
- pre-version switch --dt for old dt_size dt section remains for when --header_version 0 (default)
- add --recovery_acpio which is really just --recovery_dtbo in everything but the switch name

mkbootimg: update for boot_img_hdr_v1

- switch to v1 and write fields based on logic to still support v0 and pre-version images
- support --dt only when --header_version 0 (default), support --recovery_dtbo when --header_version 1 (or greater)
- elide some redundant code
- fix up some inconsistent bracing and spacing from previous PRs

unpackbootimg: work around new bootimg.h header_version conflict with…

… old dtbsize

stop-gap measure until boot_img_hdr_v1 can be properly integrated
Ref: https://github.com/aosp-mirror/platform_system_core/blob/master/mkbootimg/include/bootimg/bootimg.h

unpackbootimg: fix SIGSEGV in case of input / output file not available

Do not hardcode make for compatibility with *BSD.

Makefile: fix derp

unpackbootimg: support old mkbootimg format extended cmdline as well

mkbootimg: fix off-by-ones to remove enforced null termination

- per osm0sis#8 AOSP's mkbootimg no longer uses null termination at any point in the cmdline or extended cmdline fields allowing the full 512- and 1536-byte lengths, respectively; unpackbootimg already handles this correctly (thanks again @ehem)
- clean up comments/alternate code