compiling GDAL with external qhull lib fails in Windows

[dsogari]

I tried to compile GDAL with MinGW on Windwows using an external qhull library and it gave compilation errors in a few source files. I did not save the compile log to show you the error messages, sorry.

What I know for sure is that qhull has a header file called io.h, which is also distributed as part of mingw. In my case, it is located under <prefix>/x86_64-w64-mingw32/include, for 64-bit, and <prefix>/i686-w64-mingw32/include, for 32-bit).

This effectively makes the compilation fail, as the io.h file from qhull is chosen to be included instead and it does not define some symbols needed by GDAL.

[Even Rouault]

In 34637:

Try to avoid confusiong between libqhull io.h and mingw own io.h (fixes #6590)

[Even Rouault]

I hope the above would fix the issue but I didn't try on mingw/windows

[Even Rouault]

In 34641:

Rename libqhull into internal_libqhull to avoid confusing in includes when there's a /usr/include/libqhull (fixes #6590)

[dsogari]

Yes, that solves the issue. Many thanks!