WARNING
-------

Using Cmake, Clang, NDK 18b, Qt 5.12 beta 4, some Subsurface code does
not compile. At this point in time, its fully unclear to me why we see the
error as it is.

Thing fail deep down in Qt and NDK headers on #include <cmath>. Error like 
"::signbit is not in the global namespace". The most logic reason is an 
improper order in which include paths are constructed in the build process.
Any attempt to find the real reason failed. Even very similar command lines 
from a qmake build that succeed fail with a cmake style build. 

The very very dirty hack is commenting out some lines in NDK 18b:

"./android-ndk-r18b/sources/cxx-stl/llvm-libc++/include/cmath

Comment lines 313-325, and all build, links and runs with no errors 
related to this known at this point.

Signed-off-by: Jan Mulder <jlmulder@xs4all.nl>
