[evolution-mapi] Make sure intltool-merge cache is created only once

[Milan Crha <mcrha src gnome org>]

commit e99a653845c6fb2e4153986ebb8c66fed7de759d
Author: Milan Crha <mcrha redhat com>
Date:   Tue Oct 30 15:58:53 2018 +0100

    Make sure intltool-merge cache is created only once
    
    Similar to https://gitlab.gnome.org/GNOME/evolution/issues/196
    when intltool-merge is called in parallel, it could either rewrite
    the ongoing attempt to build it or use an incomplete data, which
    results in broken output files (.desktop, .metainfo and so on).
    This change ensures the intltool-merge cache is created only once
    and any other requests which would use it will wait until it's created.

 cmake/modules/FindIntltool.cmake | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)
---
diff --git a/cmake/modules/FindIntltool.cmake b/cmake/modules/FindIntltool.cmake
index 2cda254..8e223e9 100644
--- a/cmake/modules/FindIntltool.cmake
+++ b/cmake/modules/FindIntltool.cmake
@@ -176,9 +176,18 @@ macro(intltool_merge _in_filename _out_filename)
                        DEPENDS ${_in}
                )
        else(_has_no_translations)
+               if(NOT TARGET intltool-merge-cache)
+                       add_custom_command(OUTPUT ${CMAKE_BINARY_DIR}/po/.intltool-merge-cache
+                               COMMAND ${INTLTOOL_MERGE} ${_args} --quiet 
--cache="${CMAKE_BINARY_DIR}/po/.intltool-merge-cache" "${GETTEXT_PO_DIR}" "${_in}" "${_out}"
+                               DEPENDS ${_in}
+                       )
+                       add_custom_target(intltool-merge-cache ALL
+                               DEPENDS ${CMAKE_BINARY_DIR}/po/.intltool-merge-cache)
+               endif(NOT TARGET intltool-merge-cache)
+
                add_custom_command(OUTPUT ${_out}
                        COMMAND ${INTLTOOL_MERGE} ${_args} --quiet 
--cache="${CMAKE_BINARY_DIR}/po/.intltool-merge-cache" "${GETTEXT_PO_DIR}" "${_in}" "${_out}"
-                       DEPENDS ${_in}
+                       DEPENDS ${_in} intltool-merge-cache
                )
        endif(_has_no_translations)
 endmacro(intltool_merge)