toolchain/60952: musl libc headers do not provide `daddr_t`, impeding cross build on Alpine Linux host

["arcata%gmail.com@localhost via gnats" <gnats-admin%NetBSD.org@localhost>]

>Number:         60952
>Category:       toolchain
>Synopsis:       musl libc headers do not provide `daddr_t`, impeding cross build on Alpine Linux host
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Nov 02 01:20:00 +0000 2026
>Originator:     Joe Groff
>Release:        11.0-STABLE
>Organization:
>Environment:
Linux mr-pleasant 6.18.58-0-lts #1-Alpine SMP PREEMPT_DYNAMIC 2026-10-21 10:53:34 x86_64 Linux
>Description:
When doing `./build.sh tools` on an Alpine Linux 3.24.1 host, the build of `makefs` fails in several places because of a missing typedef for `daddr_t`, since musl libc does not appear to provide this typedef in the host's headers.
>How-To-Repeat:
Try, for example, `./build.sh -m evbarm -a earmv4 tools` under an Alpine Linux or other musl-based Linux host.
>Fix:
Add `typedef int64_t daddr_t;` to `tools/compat/compat_defs.h`. (A proper fix should properly conditionalize on host and target platform properties of course)