Add XZ compress support to libarchive-wrapper

This is not needed but it does not cost much to do it for all
potentially supported format in libarchive. XZ and LZMA are not
builtin libarchive and require external lib but if
CMAKE_USE_SYSTEM_LIBARCHIVE is ON then we may get it for free.

Source/cmArchiveWrite.cxx

@@ -87,6 +87,14 @@ cmArchiveWrite::cmArchiveWrite(std::ostream& os, Compress c, Type t):
         return;
         }
       break;
+    case CompressXZ:
+      if(archive_write_set_compression_xz(this->Archive) != ARCHIVE_OK)
+        {
+        this->Error = "archive_write_set_compression_xz: ";
+        this->Error += archive_error_string(this->Archive);
+        return;
+        }
+      break;
     };
 #if !defined(_WIN32) || defined(__CYGWIN__)
   if (archive_read_disk_set_standard_lookup(this->Disk) != ARCHIVE_OK)

Source/cmArchiveWrite.h

@@ -33,7 +33,8 @@ public:
     CompressNone,
     CompressGZip,
     CompressBZip2,
-    CompressLZMA
+    CompressLZMA,
+    CompressXZ
   };
 
   /** Archive Type */