btfs: depend on linux

Formula/btfs.rb

@@ -13,17 +13,10 @@ class Btfs < Formula
   depends_on "autoconf" => :build
   depends_on "automake" => :build
   depends_on "pkg-config" => :build
+  depends_on "curl"
+  depends_on "libfuse@2"
   depends_on "libtorrent-rasterbar"
-
-  uses_from_macos "curl"
-
-  on_macos do
-    disable! date: "2021-04-08", because: "requires closed-source macFUSE"
-  end
-
-  on_linux do
-    depends_on "libfuse@2"
-  end
+  depends_on :linux # on macOS, requires closed-source macFUSE
 
   def install
     ENV.cxx11
@@ -33,18 +26,6 @@ class Btfs < Formula
     system "make", "install"
   end
 
-  def caveats
-    on_macos do
-      <<~EOS
-        The reasons for disabling this formula can be found here:
-          https://github.com/Homebrew/homebrew-core/pull/64491
-
-        An external tap may provide a replacement formula. See:
-          https://docs.brew.sh/Interesting-Taps-and-Forks
-      EOS
-    end
-  end
-
   test do
     system "#{bin}/btfs", "--help"
   end