Add DESTDIR variable for qt5 inputcontext lib.

[icy]

Because DESTDIR variable's null, configure script will ignore qt5 lib
path. We set it to empty variable can make it pass qt5 lib path.

[dai-vdr]

👍

[kou]

Could you show how to confirm this problem is occurred?

[dai-vdr]

when make all, mv libuimplatforminputcontextplugin.so into /usr/plugins.

make  -f Makefile.qmake INSTALL_ROOT= all
make[4]: Entering directory '/tmp/uim/qt5/immodule'
...
mv -f libuimplatforminputcontextplugin.so /usr/plugins/platforminputcontexts/ 

if qt5/immodule/quimplatforminputcontextplugin.pro.in does not have DESITDIR, it is not passed to qt5/immodule/Makefile:

qt5/immodule/Makefile:

...
DESTDIR = 
...
# Makefile.qmake is only exist when --enable-qt5-immodule
all clean mocclean install uninstall:
        $(MAKE) $(AM_MAKEFLAGS) -f Makefile.qmake INSTALL_ROOT=$(DESTDIR) $@
...

qt5/immodule/Makefile.qmake:

/usr/plugins/platforminputcontexts/$(TARGET):  $(OBJECTS) $(SUBLIBS) $(OBJCOMP) 

        @test -d /usr/plugins/platforminputcontexts/ || mkdir -p /usr/plugins/platforminputcontexts/
        -$(DEL_FILE) $(TARGET)
        $(LINK) $(LFLAGS) -o $(TARGET) $(OBJECTS) $(LIBS) $(OBJCOMP)
        -$(MOVE) $(TARGET) /usr/plugins/platforminputcontexts/