[Interest] Struggling to build qt 5.9.9 for iOS

[maitai]

Hi,
I need to build qt5.9.9 since I cannot wait for its release end 2019, 
due to qtbug-70683.

I am trying to build with what I have, i.e. XCode 10.2.1 SDK iOS 12.2

After I run configure and make, I get a compilation error:

  items/qquickshadereffect.cpp:511:20: error: aligned allocation function 
of type
       'void *(unsigned long, enum std::align_val_t)' is only available 
on iOS 11
       or newer
         m_glImpl = new QQuickOpenGLShaderEffect(this, this);
                    ^
items/qquickshadereffect.cpp:511:20: note: if you supply your own 
aligned
       allocation functions, use -faligned-allocation to silence this 
diagnostic
1 error generated.

So then after some researches I tried to add -c++std c++14 to configure

This time all build OK, but when I try to build my application with this 
qt version, I get at the end, during the LD phase:

Undefined symbols for architecture arm64:
   "_inflateValidate", referenced from:
       _png_inflate_claim in libqtlibpng.a(pngrutil.o)
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see 
invocation)

So, no joy... Tried many other things, and each trial takes hours

So basically the question is:
What are the correct configure options to build qt5.9.9 for iOS?

Thanks
Philippe.