CMakeLists: Ensure proper numerusform tags are generated for pluralized translations

If we don't set an explicit source and target language for the base
english translation, then we'll generate an incorrect number of
<numerusform> tags (which Transifex doesn't like).

src/yuzu/CMakeLists.txt

@@ -182,7 +182,14 @@ if (ENABLE_QT_TRANSLATION)
     # Update source TS file if enabled
     if (GENERATE_QT_TRANSLATION)
         get_target_property(SRCS yuzu SOURCES)
-        qt5_create_translation(QM_FILES ${SRCS} ${UIS} ${YUZU_QT_LANGUAGES}/en.ts)
+        qt5_create_translation(QM_FILES
+            ${SRCS}
+            ${UIS}
+            ${YUZU_QT_LANGUAGES}/en.ts
+        OPTIONS
+            -source-language en_US
+            -target-language en_US
+        )
         add_custom_target(translation ALL DEPENDS ${YUZU_QT_LANGUAGES}/en.ts)
     endif()