* configure.ac: Check for dlopen in libc before trying -ldl. On musl
(and OpenHarmony), dlopen is part of libc with no separate libdl.
* configure.ac: Add _LARGEFILE64_SOURCE fallback detection for fopen64.
On musl, fopen64 needs this define to be declared; glibc exposes it
via _LARGEFILE_SOURCE alone.
* config.guess: Recognize HarmonyOS uname -s output and canonicalize
as *-unknown-linux-ohos.
sailor001
Cary R
a1ca7raz
Martin Whitaker
steve