Merge pull request ocaml#27736 from Leonidas-from-XIV/core-unix-glibc

`core_unix` does not build on non-glibc Linux

Author: mseri

packages/core_unix/core_unix.v0.16.0/opam

@@ -29,8 +29,7 @@ synopsis: "Unix-specific portions of Core"
 description: "
 Unix-specific extensions to some of the modules defined in [core] and [core_kernel].
 "
-depexts: ["linux-headers"] {os-family = "alpine"}
-available: [ !(os = "freebsd" & os-version >= "14") ]
+available: [ !(os = "freebsd" & os-version >= "14") & os-distribution != "alpine" ]
 url {
 src: "https://ocaml.janestreet.com/ocaml-core/v0.16/files/core_unix-v0.16.0.tar.gz"
 checksum: "sha256=4f70a9d3a761799d00c0a207942b4abd9f1a144bbcb19df98021d9fb7bfa9e5f"

packages/core_unix/core_unix.v0.17.0/opam

@@ -25,7 +25,7 @@ depends: [
   "dune"                     {>= "3.11.0"}
   "spawn"                    {>= "v0.15"}
 ]
-available: [ (arch = "x86_64" | arch = "arm64") & !(os = "freebsd" & os-version >= "14") ]
+available: [ (arch = "x86_64" | arch = "arm64") & !(os = "freebsd" & os-version >= "14") & os-distribution != "alpine"]
 synopsis: "Unix-specific portions of Core"
 description: "
 Unix-specific extensions to some of the modules defined in [core] and [core_kernel].