Add ability to build GnuCash with CMake

Backported from master.

po/CMakeLists.txt

@@ -0,0 +1,48 @@
+
+
+# Set of available languages.
+SET (TP_LINGUAS az ca cs da eu fa ja nl pt rw sk sr sv tr uk zh_CN)
+# already marked as external at TP:
+SET (GC_LINGUAS ar bg de el en_GB es fi fr gu he hi hu it kn ko lt lv mr nb ne pl pt_BR ro ru ta te ur vi zh_TW)
+# not marked or no TP team:
+SET (NEW_LINGUAS as brx doi es_NI kok kok@latin ks mai mni mni@bengali)
+
+SET (ALL_LINGUAS ${TP_LINGUAS} ${GC_LINGUAS} ${NEW_LINGUAS})
+
+SET (CATALOGS "")
+SET (BUILD_CATALOGS "")
+FOREACH(lingua ${ALL_LINGUAS})
+  SET(_OUTPUT_FILE ${lingua}.gmo)
+  LIST(APPEND CATALOGS ${_OUTPUT_FILE})
+  ADD_CUSTOM_COMMAND(
+      OUTPUT ${_OUTPUT_FILE}
+      COMMAND ${CMAKE_COMMAND} -E env ${MSGFMT} -o ${_OUTPUT_FILE} ${CMAKE_CURRENT_SOURCE_DIR}/${lingua}.po
+  )
+  IF (GNC_BUILD_AS_INSTALL)
+    SET(_BUILD_FILE_DIR ${DATADIR_BUILD}/locale/${lingua}/LC_MESSAGES)
+    MAKE_DIRECTORY(${_BUILD_FILE_DIR})
+    SET(_BUILD_FILE ${_BUILD_FILE_DIR}/gnucash.gmo)
+    LIST(APPEND BUILD_CATALOGS ${_BUILD_FILE})
+    #ADD_CUSTOM_COMMAND(
+    #  OUTPUT ${_BUILD_FILE}
+    #  COMMAND ${CMAKE_COMMAND} make_directory ${_BUILD_FILE_DIR}
+    #
+    #)
+    ADD_CUSTOM_COMMAND(
+      OUTPUT ${_BUILD_FILE}
+      COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_BINARY_DIR}/${lingua}.gmo ${_BUILD_FILE}
+      DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/${_OUTPUT_FILE}
+      #APPEND
+    )
+  ENDIF()
+ENDFOREACH(lingua)
+
+ADD_CUSTOM_TARGET(po-gmo ALL DEPENDS ${CATALOGS})
+IF (GNC_BUILD_AS_INSTALL)
+  ADD_CUSTOM_TARGET(po-gmo-build ALL DEPENDS ${BUILD_CATALOGS})
+ENDIF()
+
+
+FOREACH(lingua ${ALL_LINGUAS})
+  INSTALL(FILES ${CMAKE_CURRENT_BINARY_DIR}/${lingua}.gmo RENAME gnucash.mo DESTINATION share/locale/${lingua}/LC_MESSAGES)
+ENDFOREACH(lingua)