fix marshalling for bool ret

Author: aloneguid

managed/IronCompress/Iron.cs

@@ -48,7 +48,9 @@ public static bool SupportsNative(Codec c) {
         }
 
         public static string GetNativeVersion() {
-            return Native.iron_version();
+            IntPtr ptr = Native.iron_version();
+            string version = Marshal.PtrToStringAnsi(ptr);
+            return version;
         }
 
         /// <summary>

managed/IronCompress/Native.cs

@@ -47,12 +47,14 @@ internal static extern unsafe bool iron_compress(bool compress,
             int compressionLevel);
 
         [DllImport(LibName)]
+        [return: MarshalAs(UnmanagedType.I1)]
         internal static extern bool iron_ping();
 
         [DllImport(LibName)]
+        [return: MarshalAs(UnmanagedType.I1)]
         internal static extern bool iron_is_supported(int codec);
 
         [DllImport(LibName)]
-        internal static extern string iron_version();
+        internal static extern IntPtr iron_version();
     }
 }