libxml2: generate symbols for --enable-dbgutil builds

Change-Id: I46df2800eb3440ee6c139867cf00f5cad5c4f3f1
Reviewed-on: https://gerrit.libreoffice.org/32012Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

external/libxml2/ExternalProject_xml2.mk

@@ -34,6 +34,7 @@ $(call gb_ExternalProject_get_state_target,xml2,build):
 	$(call gb_ExternalProject_run,build,\
 		cscript /e:javascript configure.js \
 			iconv=no icu=yes sax1=yes $(if $(MSVC_USE_DEBUG_RUNTIME),run_debug=yes cruntime=/MDd) \
+			$(if $(filter TRUE,$(ENABLE_DBGUTIL)),debug=yes) \
 		&& unset MAKEFLAGS \
 		&& LIB="$(ILIB)" nmake \
 	,win32)