capstone: enable for darwin, enable tests & fix pkg-config output

turns out capstone.pc is generated during the buildPhase, so needs
PREFIX set here too for it to be correct

pkgs/development/libraries/capstone/default.nix

@@ -9,9 +9,23 @@ stdenv.mkDerivation rec {
     sha256 = "1isxw2qwy1fi3m3w7igsr5klzczxc5cxndz0a78dfss6ps6ymfvr";
   };
 
+  # replace faulty macos detection
+  postPatch = stdenv.lib.optionalString stdenv.isDarwin ''
+    sed -i 's/^IS_APPLE := .*$/IS_APPLE := 1/' Makefile
+  '';
+
   configurePhase = '' patchShebangs make.sh '';
-  buildPhase = '' ./make.sh '';
-  installPhase = '' env PREFIX=$out ./make.sh install '';
+  buildPhase = "PREFIX=$out ./make.sh";
+
+  doCheck = true;
+  checkPhase = ''
+    # first remove fuzzing steps from check target
+    substituteInPlace Makefile --replace "fuzztest fuzzallcorp" ""
+    make check
+  '';
+
+  installPhase = (stdenv.lib.optionalString stdenv.isDarwin "HOMEBREW_CAPSTONE=1 ")
+    + "PREFIX=$out ./make.sh install";
   
   nativeBuildInputs = [
     pkgconfig
@@ -23,7 +37,7 @@ stdenv.mkDerivation rec {
     description = "Advanced disassembly library";
     homepage    = "http://www.capstone-engine.org";
     license     = stdenv.lib.licenses.bsd3;
-    platforms   = stdenv.lib.platforms.linux;
-    maintainers = [ stdenv.lib.maintainers.thoughtpolice ];
+    platforms   = stdenv.lib.platforms.unix;
+    maintainers = with stdenv.lib.maintainers; [ thoughtpolice ris ];
   };
 }