QNX: Force use of system zlib on Windows host

While we on Linux will do a compile test to check for a
system zlib, the test on a Windows host was less accurate, causing
us to compile in the zlib from 3rdparty/ here. This caused compilation
errors after updating the freetype font engine to support color fonts,
since the zlib in 3rdparty/ was included implicitly in the freetype
library, and since it depends on Qt headers, the compilation failed
in this context.

The hotfix is to force system zlib on QNX for Windows hosts, since
we know it is available in the NDK. Doing a proper build check is not
worth it right now, due to future plans for changing configure. We
will still break for an explicit -qt-zlib compilation, so the plan is
to fix this in an upcoming commit by separating libpng into
a library.

The hotfix just follows e6cb3b8c.

Task-number: QTBUG-53248
Change-Id: I07dd4356fae6397b3cc93fc1fa97bf35380e19df
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@theqtcompany.com>
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

0 files changed, 0 insertions, 0 deletions