alsaLib: fix build under musl-libc (#110413)

* alsaLib: fix build under musl-libc

there's a commit in upstream master that fixes the build issue here.
this patch is also applied in alpine linux.

* alsaLib: explainer for DL_ORIGIN patch

pkgs/os-specific/linux/alsa-lib/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, fetchurl, alsa-ucm-conf, alsa-topology-conf }:
+{ lib, stdenv, fetchurl, fetchpatch, alsa-ucm-conf, alsa-topology-conf }:
 
 stdenv.mkDerivation rec {
   pname = "alsa-lib";
@@ -11,6 +11,14 @@ stdenv.mkDerivation rec {
 
   patches = [
     ./alsa-plugin-conf-multilib.patch
+    (fetchpatch {
+      # plucked from upstream master, delete in next release
+      # without this patch alsa 1.2.4 fails to compile against musl-libc
+      # due to an overly conservative ifdef gate in a new feature
+      name = "fix-dlo.patch";
+      url = "https://github.com/alsa-project/alsa-lib/commit/ad8c8e5503980295dd8e5e54a6285d2d7e32eb1e.patch";
+      sha256 = "QQP4C1dSnJP1MNKt2el7Wn3KmtwtYzvyIHWdrHs+Jw4=";
+    })
   ];
 
   enableParallelBuilding = true;