CMake: Set OUTPUT_NAME on plugin libraries to the correct language name

Work around CMake's handling of @ inside argument names that then end up
getting defined as variable names in language_plugin as well. We also need
to set the OUTPUT_NAME of these plugins back to the unmodified language
value, so that the plugins can be properly loaded by the keyboard.

CMakeLists.txt

@@ -205,21 +205,29 @@ target_include_directories(westernsupport PUBLIC src/lib/logic plugins/westernsu
 target_compile_definitions(westernsupport PRIVATE ${maliit-keyboard-definitions})
 
 function(language_plugin _language _full_language _ebook)
+    # To support layout style variations such as en@dv we need to avoid using
+    # the @ character in variables, so split and replace it with _
+    set(_target ${_language})
+    if(${_language} MATCHES "^(.*)\@(.*)$")
+        set(_target ${CMAKE_MATCH_1}_${CMAKE_MATCH_2})
+    endif()
+
     set(PLUGIN_SOURCES
             plugins/${_language}/src/${_full_language}plugin.h
             plugins/${_language}/src/${_full_language}plugin.json)
 if(enable-presage)
     add_ngram(TEXT plugins/${_language}/src/${_ebook} DATABASE database_${_language}.db)
     list(APPEND PLUGIN_SOURCES database_${_language}.db)
 endif()
-    add_library(${_language}plugin MODULE ${PLUGIN_SOURCES})
-    target_link_libraries(${_language}plugin maliit-keyboard-common westernsupport)
+    add_library(${_target}plugin MODULE ${PLUGIN_SOURCES})
+    set_target_properties(${_target}plugin PROPERTIES OUTPUT_NAME ${_language}plugin)
+    target_link_libraries(${_target}plugin maliit-keyboard-common westernsupport)
     install(FILES plugins/${_language}/qml/Keyboard_${_language}.qml
             plugins/${_language}/qml/Keyboard_${_language}_email.qml
             plugins/${_language}/qml/Keyboard_${_language}_url.qml
             plugins/${_language}/qml/Keyboard_${_language}_url_search.qml
             DESTINATION ${MALIIT_KEYBOARD_LANGUAGES_DIR}/${_language})
-    install(TARGETS ${_language}plugin
+    install(TARGETS ${_target}plugin
             LIBRARY DESTINATION ${MALIIT_KEYBOARD_LANGUAGES_DIR}/${_language})
 if(enable-presage)
     install(FILES ${CMAKE_CURRENT_BINARY_DIR}/database_${_language}.db
@@ -277,6 +285,7 @@ function(abstract_language_plugin _language _full_language)
         list(APPEND PLUGIN_SOURCES database_${_language}.db)
     endif()
     add_library(${_target}plugin MODULE ${PLUGIN_SOURCES})
+    set_target_properties(${_target}plugin PROPERTIES OUTPUT_NAME ${_language}plugin)
     target_link_libraries(${_target}plugin Qt5::Core Maliit::Plugins maliit-keyboard-common ${abstract_language_plugin_LIBRARIES})
     target_include_directories(${_target}plugin PRIVATE src/lib/logic ${abstract_language_plugin_INCLUDE_DIRS})
     target_compile_definitions(${_target}plugin PRIVATE ${abstract_language_plugin_DEFINITIONS})