Qt and subsurface for Android

[Willem Ferguson]

I am trying to build subsurface for execution on Android in order to 
test the FTDI support. However I get the following error:

~/src$ export SUBSURFACE_DESKTOP=ON
~/src$ printenv | grep "SUBSURFACE_DESKTOP"
SUBSURFACE_DESKTOP=ON
~/src$ bash subsurface/packaging/android/build.sh
~/src/subsurface ~/src
~/src
Cannot find Qt 5.7, 5.6 or 5.5 under /home/willem/src/subsurface/../Qt

This should not be a surprise, because I work with a new install of 
Ubuntu and I have not explicitly installed Qt yet. However, the Linux 
desktop version of Subsurface builds perfectly on this machine, so some 
Qt must exist. Is this correct? How can I find the version of the 
installed Qt?

Upon closer inspection, it looks like /scripts/build.sh expects either 
Qt 5.5 or 5.6, as opposed to the Android build.sh that expects 5.5, 5.6 
or 5.7.

Where would the optimal place be to install it into? If I install Qt, I 
would expect to install 5.7.  What does 
"/home/willem/src/subsurface/../Qt" mean? Qt within the subsurface 
folder? Cannot be.

How can I point the build.sh to an appropriate location?

Kind regards,

willem