Remove leftover "#undef DEBUG"

...which might have had a purpose in the past, but look unused today.  (DEBUG is
defined in solenv/gbuild/gbuild.mk iff dbglevel >= 2, and `make
Library_xsec_xmlsec dbglevel=2` doesn't run into any problems for me with the
undefs removed.)

Change-Id: I7f941e8c2d454f4206fb17bc791247606ffe6309
Reviewed-on: https://gerrit.libreoffice.org/54718Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

xmlsecurity/source/xmlsec/nss/nssinitializer.cxx

@@ -17,13 +17,6 @@
  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  */
 
-
-/*
- * and turn off the additional virtual methods which are part of some interfaces when compiled
- * with debug
- */
-#undef DEBUG
-
 #include <com/sun/star/lang/IllegalArgumentException.hpp>
 #include <com/sun/star/mozilla/XMozillaBootstrap.hpp>
 #include <com/sun/star/xml/crypto/DigestID.hpp>

xmlsecurity/source/xmlsec/nss/seinitializer_nssimpl.cxx

@@ -17,14 +17,6 @@
  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  */
 
-/*
- * and turn off the additional virtual methods which are part of some interfaces when compiled
- * with debug
- */
-#ifdef DEBUG
-#undef DEBUG
-#endif
-
 #include <comphelper/processfactory.hxx>
 #include <sal/types.h>
 #include <rtl/bootstrap.hxx>