textproc/fcitx5-mcfoxim: Fix build by depending on ECM directly

The top-level CMakeLists.txt calls find_package(ECM REQUIRED 1.0.0) and
find_package(Gettext REQUIRED), but the port never declared either
dependency. It only built because textproc/fcitx5 pulled ECM and
gettext-tools in at run time. Since 95f9a6808973 dropped the ECM run
dependency, explicitly depending on gettext and ecm is required (and correct).