[evolution-mapi] Missing build dependency for gdbus-codegen on input .xml file

[Milan Crha <mcrha src gnome org>]

commit 6f715d1679b550d6720131b98d1eaa672abf169a
Author: Milan Crha <mcrha redhat com>
Date:   Mon Jun 11 10:13:55 2018 +0200

    Missing build dependency for gdbus-codegen on input .xml file
    
    Related to https://gitlab.gnome.org/GNOME/evolution-data-server/issues/7

 cmake/modules/GLibTools.cmake | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/cmake/modules/GLibTools.cmake b/cmake/modules/GLibTools.cmake
index f0be558..d40953c 100644
--- a/cmake/modules/GLibTools.cmake
+++ b/cmake/modules/GLibTools.cmake
@@ -175,6 +175,7 @@ function(gdbus_codegen_custom _xml _interface_prefix _c_namespace _files_prefix
                        --generate-docbook ${_files_prefix}
                        ${_args}
                        ${CMAKE_CURRENT_SOURCE_DIR}/${_xml}
+               MAIN_DEPENDENCY ${CMAKE_CURRENT_SOURCE_DIR}/${_xml}
                VERBATIM
        )
 endfunction(gdbus_codegen_custom)