webrtc-audio-processing: tighten platforms

webrtc-audio-processing only builds for specifically listed
architectures, so we shouldn't mark it as being supported on all of
them.

I've also changed the x86_32 breakage to be marked with meta.broken,
as it's more semantically appropriate.

pkgs/development/libraries/webrtc-audio-processing/0.3.nix

···
     homepage = "https://www.freedesktop.org/software/pulseaudio/webrtc-audio-processing";
     description = "A more Linux packaging friendly copy of the AudioProcessing module from the WebRTC project";
     license = licenses.bsd3;
-    platforms = platforms.unix;
+    # https://gitlab.freedesktop.org/pulseaudio/webrtc-audio-processing/-/blob/v0.3.1/webrtc/rtc_base/system/arch.h
+    # + our patches
+    platforms = intersectLists platforms.unix (platforms.aarch64 ++ platforms.mips ++ platforms.power ++ platforms.riscv ++ platforms.x86);
   };
 }

pkgs/development/libraries/webrtc-audio-processing/default.nix

···
     homepage = "https://www.freedesktop.org/software/pulseaudio/webrtc-audio-processing";
     description = "A more Linux packaging friendly copy of the AudioProcessing module from the WebRTC project";
     license = licenses.bsd3;
+    # https://gitlab.freedesktop.org/pulseaudio/webrtc-audio-processing/-/blob/master/webrtc/rtc_base/system/arch.h
+    platforms = intersectLists platforms.unix (platforms.aarch64 ++ platforms.mips ++ platforms.riscv ++ platforms.x86);
     # attempts to inline 256bit AVX instructions on x86
     # https://gitlab.freedesktop.org/pulseaudio/webrtc-audio-processing/-/issues/5
-    platforms = lib.lists.subtractLists platforms.i686 platforms.unix;
+    broken = stdenv.isx86_32;
   };
 }