First some cosmetic things.

Please squash all the commits into one. You don't have to wait for approval after you made any changes to the PR.

Please use the tab charater for indentation in build.sh.

The dependency is dubious, according to DT_NEEDED entries in the ELF objects.

mozc-ut

libQt5Core.so.5
libQt5Gui.so.5
libQt5Widgets.so.5
libandroid-execinfo.so
libandroid-posix-semaphore.so
libc++_shared.so
libc.so
libdl.so
libiconv.so
libm.so

So the dependency should at least include

fcitx5, libandroid-execinfo, libandroid-posix-semaphore, libc++, libiconv, qt5-qtbase

fcitx5-mozc-ut

libFcitx5Config.so
libFcitx5Core.so
libFcitx5Utils.so
libandroid-posix-semaphore.so
libc++_shared.so
libc.so
libdl.so
libm.so

This subpackage depends on the parent package and so no need to specify extra dependencies.

mozc-ut-emacs

libandroid-posix-semaphore.so
libc++_shared.so
libc.so
libm.so

No problem. (Obviously emacs should be depended on.)

Thank you for reviewing.

I refined package dependencies and squash all commits.

So the dependency should at least include

fcitx5, libandroid-execinfo, libandroid-posix-semaphore, libc++, libiconv, qt5-qtbase

Well, mozc-ut is not depend to fcitx5, I think.
(If you want to use mozc-ut only with emacs, you need to install mozc-ut and mozc-ut-emacs. Installing fcitx5-mozc-ut and fcitx5 are not required.)