build system: work around strange cmake issue

On both Mac and Linux cmake 3.12 complained that there were "no sources given
to target" for the Subsurface-mobile target, which made no sense at all (easy
enough to add debug output to ensure there were, in fact, sources given in the
call to add_executable()). But splitting this across two lines like this seems
to make it work both for older and newer cmake versions.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

0 files changed, 0 insertions, 0 deletions