Have CMake call "$(MAKE) -C doc xmlwf.1"

.. so that the man page is built if missing (e.g. for a Git clone)
diff --git a/expat/CMakeLists.txt b/expat/CMakeLists.txt
index 5cdd301..839ab44 100755
--- a/expat/CMakeLists.txt
+++ b/expat/CMakeLists.txt
@@ -84,6 +84,7 @@
 install(FILES ${CMAKE_CURRENT_BINARY_DIR}/expat.pc DESTINATION lib/pkgconfig)

 

 

+add_custom_command(TARGET expat PRE_BUILD COMMAND $(MAKE) -C doc xmlwf.1)

 

 if(BUILD_tools AND NOT WINCE)

     set(xmlwf_SRCS