[kdenlive] build script ver 27

[Roger Morton]

So I got a modified version of build script ver 27 to work.  My instal
failure was due to a stuff-up on my part.

However, the script as written does not work for me.  Two things
needed changing.

1.   need a DQT_QMAKE_EXECUTABLE var in the cmake config line

CONFIG[2]="cmake .. -DCMAKE_INSTALL_PREFIX=$FINAL_INSTALL_DIR
-DCMAKE_BUILD_TYPE=RelWithDebInfo"

becomes

CONFIG[2]="cmake   -DCMAKE_INSTALL_PREFIX=$FINAL_INSTALL_DIR
-DCMAKE_BUILD_TYPE=RelWithDebInfo -DQT_QMAKE_EXECUTABLE=$QMAKE"

2.  "Special hack for kdenlive" bit ~ line 1153 - the "cmd cd build"
fails and is not necessary

I am still maintaining a version that works for me at
https://community.kde.org/Kdenlive/Development/KF5#A_build_script

Vincent - can we get our heads together to figure out how to make a
universal version that could work for both of us (and others)?